16JOURNAL OF CLIMATE
The Meteorological Observations of Jean-Franc¸ois Gaultier, Quebec, Canada: 1742–56
Climate Research Branch, Meteorological Service of Canada (Environment Canada), Toronto, Ontario, Canada
(Manuscript received 3 January 2002, in ﬁnal form 11 November 2002)
Jean-Franc¸ois Gaultier was a physician in the French colony of Que´bec in New France from 1742 to 1756.
During that period, he recorded daily readings of temperature and observations of the weather, although only
the observations for 1742–46, 1747–48, and 1754 have been located to date. Daily instrumental temperature
data from Que´bec for the 1740s provide a glimpse of climate variability in eastern North America, upstream of
the North Atlantic. During the 1740s, winters appear to have been milder than during most of the twentieth
century with the exception of the 1950s and early 1980s, and summers warmer than those of the twentieth
century, with the exception of the 1970s and 1990s. Autumns and springs appear to have been cool relative to
the twentieth century, suggesting that, while winters may have been milder, the winter season lasted longer, with
a consequently shorter growing season. The cool springs and autumns,combined with warm winters and summers,
give these few years in the 1740s annual average temperatures comparable to those averaged over the twentieth
century; the annual average temperatures mask marked seasonal differences. There is also some evidence that
the climate was drier than in recent times, with fewer precipitation days than during the 1970–2000 period.
The study of recent climate variability, on the decadal
to century timescale, is of critical importance to un-
derstanding present and future climate change. Anthro-
pogenic climate change is superimposed on a natural
climate variability, which is still poorly understood on
a regional scale (Mann et al. 1998). While relatively
complete climate datasets exist for the last 50 years, and
some even for the past 100 years (e.g., Jones et al. 1999;
New et al. 2000), it is necessary to better understand
the variations and trends of climate over the past 200
to 500 years in order to place in context those of the
past 50 years. This is also necessary to increase our
conﬁdence in both our understanding of climate pro-
cesses and in future climate predictions on the inter-
annual to decadal scale. Historical data, particularly in-
strumental observations, are essential to our understand-
ing of past climate changes. Such data can be found in
the records kept by amateur meteorologists in the pe-
riods before the establishment of national meteorolog-
* Current afﬁliation: Ouranos Consortium for Regional Climate
Change and Adaptation, Department of Atmospheric and Oceanic
Sciences, McGill University, Montreal, Quebec, Canada.
Corresponding author address: Dr. Victoria Slonosky, Ouranos
Consortium for Regional Climate Change and Adaptation, Depart-
ment of Atmospheric and Oceanic Sciences, McGill University, 550
Sherbrooke St. W, 19th ﬂoor, West Tower, Montreal QC H3A 1B9,
ical agencies in the mid to late nineteenth century (e.g.,
Manley 1953, 1962, 1974; Legrand and LeGoff 1992;
Slonosky et al. 2001b). These data can give valuable
insights into the variability and behavior of climate dur-
ing the period before the impact of industrialization,
help evaluate the natural variability of climate, andplace
recent climate change into a longer-term perspective
(Folland et al. 2001).
Current ideas of climatic change of the past 500 years
are dominated by the concept of the ‘‘Little Ice Age,’’
a period of worldwide glacier advances lasting from the
thirteenth to the nineteenth centuries (Grove 2001). The
evolution of climate during this period is somewhat
more complex, with cooler temperatures particularly in
the seventeenth and nineteenth centuries, and subse-
quent recovery to warmer conditions during the twen-
tieth century, along with anthropogenic climatic change
during the late twentieth century (Jones 1998; Mann et
al. 1998; Crowley 2000). Recent advances in the ﬁeld
of historical climatology have added considerably to this
picture, building a more complex and detailed picture
of the climatic changes that have occurred over the past
few centuries (e.g., Wilson 1983; Harrington 1992; Le-
grand and LeGoff 1992; Pﬁster et al. 1994; Mann et al.
1995; Luterbacher et al. 1999, 2002; Moberg et al. 2000;
Auer et al. 2001; Demare´e and Ogilvie 2001; Jo´nsson
and GarUarsson 2001; van Engelen et al. 2001). Con-
siderable interannual climatic variability existed during
all these periods, with alternating years and even alter-
nating seasons of extreme wet or dry conditions (Slon-
osky 2002), and months or seasons of extreme warmth
and cold linked to variability of the atmospheric cir-
culation (Luterbacher et al. 2000; Jacobeit et al. 2001;
Shindell et al. 2001; Slonosky et al. 2001a,b) in the
seventeenth and eighteenth centuries. The use of early
instrumental meteorological records has also led to sev-
eral extremely important developments in the past few
years, including the extension of an index of the North
Atlantic Oscillation (NAO)—one of the most important
modes of atmospheric circulation in the Northern Hemi-
sphere—on a monthly scale back to 1822 using instru-
mental data (Jones et al. 1997), and back to 1675 on a
monthly scale and 1500 on a seasonal scale using his-
torical documentary data (Luterbacher et al. 1999,
2002). These reconstructions enable the study of cli-
matic change and climate variability to be extended over
several hundreds of years, and the dynamics of the at-
mospheric circulation over these periods to be examined
in detail (Jacobeit et al. 2001; Slonosky et al. 2001a).
The years of interest to this study, the 1740s and
1750s, were during the cool centuries of the Little Ice
Age, but after the period of very low solar activity
known as the Late Maunder Minimum (LMM) from
1675 to 1715, during which the climate was particularly
severe in Europe (e.g., Pﬁster et al. 1994; Legrand and
LeGoff 1992; Slonosky et al. 2001b; Luterbacher et al.
2002). The seventeenth century was the coldest of the
past millenium, followed by the nineteenth (Jones et al.
2001). During the eighteenth century, Northern Hemi-
sphere temperatures were on the order of 0.38C lower
than those of the late twentieth century, the 1750s show-
ing a relatively warm peak in the Northern Hemisphere
temperature records, compared to lower temperaturesin
the 1680s and 1690s and 1800–50 (Jones 1998; Mann
et al. 1998; Jones et al. 2001).
Although it is not easy, and sometimes not possible,
to adjust historical data to conform to modern standards,
some adjustments can be made to account for the likely
impacts of more primitive instruments and different ob-
serving practices than those in use today. The keen in-
terest of the early amateur observers, their intelligent
use of their instruments and interpretation of their ob-
servations can sometimes compensate a great deal for
the deﬁciencies in the instruments (Manley 1953, 1962,
1974; Legrand and LeGoff 1992; Slonosky et al. 2001b;
Slonosky 2002). Despite the limitations of historical in-
strumental records, even after calibration to modern
standards, some conclusions may be drawn as to the
general character of the seasons and the interannual var-
iability of the period for which the data exist.
This paper examines historical climate data that has
been largely forgotten by the climatological community,
recently found in the Paris Observatory in France. Re-
cords of daily temperature readings, weather observa-
tions, and observations of the state of agriculture and
vegetation were kept by Dr. Jean-Franc¸ois Gaultier, who
was sent as the king’s physician to the French colony
at Que´bec for the period 1742–56. These are the earliest
known instrumental meteorological observations for
Canada, and among the earliest of the North American
continent (Baron 1992). The instrumental observations
and adjustments to modern observing standards are dis-
cussed in section 2. In section 3, a description of the
climate during the 1740s is given, based on both the
instrumental observations and Gaultier’s descriptiveand
phenological observations. A comparison between the
climate of the 1740s and that of Que´bec City today is
given in section 4, followed by a discussion of Gaultier’s
data in the context of other historical and paleoclimatic
observations, as well as reconstructions of atmospheric
dynamics, in the ﬁnal section.
2. The meteorological observations of Jean-
Jean-Franc¸ois Gaultier (1708–56) was a physician ed-
ucated in Paris, and sent to the city of Que´bec in 1742
as the king’s physician to the colony in New France.
He was a corresponding member of the Acade´mie Roy-
ale des Sciences, corresponding with H. Duhamel du
Monceau and later with R.A.F. Re´aumur on the botany
of the New World, its climate and on his thermometric
experiments. His daily thermometric measurements,
precipitation-type observations, wind direction, and
weather descriptions were printed in the Me´moires de
l’Acade´mie Royale des Sciences (Fig. 1; Duhamel du
Monceau 1744, 1745, 1746, 1747). Manuscript obser-
vation diaries also exist at the Paris Observatory for
1744/45, 1747/48, and at the Houghton Library of Har-
vard University for 1754 (Gaultier 1745, 1748, 1755).
Gaultier recorded monthly summaries of the weather,
the state of the colony’s agriculture, which was highly
dependent on the weather for crop growth and favorable
planting and harvesting conditions, and the public health
of the colony. He remained in Que´bec City until his
death in 1756. His scientiﬁc contributions, particularly
his accomplishments in the ﬁelds of botany and mete-
orology, and the quality of his phenological observa-
tions have been recognized by historians (Valle´e 1930;
Wien 1990). Evidence suggests that he kept meteoro-
logical records during this entire period, although sev-
eral years of observations appear to have been unfor-
The thermometer readings were almost always taken
in morning, between 0700 and 0800 local time (LT) and
occasionally also in the afternoon between 1400 and
1500 LT (Fig. 1). The morning readings are quite con-
sistent, with only 1.6% of observations missing. How-
ever, the afternoon readings were only taken occasion-
ally, and seem to have been recorded particularly when
the afternoon temperature was warm for the time of year.
Most of the afternoon temperatures are recorded on mild
winter days, in spring, and in summer.
The thermometer readings have been converted from
Gaultier’s scale, which was based upon that of Delisle
for 1742–48 (Duhamel du Monceau 1744). Gaultier’s
early thermometer was made of mercury and his scale
16JOURNAL OF CLIMATE
. 1. Printed page of Gaultier’s weather observations in the Me´-
moires de l’Acade´mie Royale des Sciences (Duhamel du Monceau
designated 0 as the freezing point of water, but put 100
at the boiling point of alcohol, or about 808C (Middleton
1966); these values were converted into a centigrade
scale. By 1754 however, Gaultier seems to have ac-
quired a centigrade thermometer. There is a bias against
extremely cold days, as the mercury in Gaultier’s early
thermometer contracted into the bulb at about 2238C,
although Gaultier still attempted to quantify the degree
of contraction. For the purposes of this study, an ap-
proximation has been made by replacing days on which
Gaultier’s thermometer fell to below 2238C with an
extreme value calculated as the modern daily mean min-
imum value minus two standard deviations. The daily
mean minus two standard deviations was found to pro-
vide the best estimated value consistent with the evo-
lution of the daily temperature during these cold spells,
producing no sudden jumps in the record. Eighteen days
were replaced in this manner during 1742/43, four dur-
ing 1743/44, two during 1744/45 and 1745/46, and six
during 1774/48; none were replaced in 1754. It was
decided to use these estimated values to replace the
temperature values for these days of extreme cold in
preference to coding the values as missing, in order to
bias the data as little as possible; coding these days as
missing would have introduced a warm bias in the data.
(This problem faced by Gaultier in Canada as well as
by observers in parts of Russia led to the development
and calibration of new thermometers with an extended
Figures 2a and 2b show the daily morning and af-
ternoon readings, together with the mean plus and minus
one and two standard deviations from the modern Que´-
bec minimum (Fig. 2a) and maximum (Fig. 2b) tem-
peratures, adjusted for Que´bec City. The current obser-
vation location is at Que´bec City airport, a small re-
gional airport. See Vincent et al. (2002) for details of
the homogenization of daily temperatures. The adjust-
ment factor determined by Vincent to render the Que´bec
City series homogenous, given several site relocations
(including one from the city center to the airport),ranges
from 22.78C in February to 21.38C in May for max-
imum temperature, no adjustments were needed for min-
imum temperature (L. Vincent 2001, personal com-
munication). Gaultier’s values generally fall within the
expected range of temperature values. As the minimum
temperature usually occurs near sunrise under normal
clear sky radiative conditions, Gaultier’s ﬁxed-hour ob-
servations are taken close to the time the minimum tem-
perature occurs in winter, but are a few hours later in
summer. His summer morning values are thus higher
than the minimum Que´bec temperatures in summer.
Figure 3 shows the estimated maximum and minimum
temperatures estimated from Gaultier’s readings. These
estimates were made by calculating the difference be-
tween the 0800 LT and minimum temperature for each
day of the year, and the 1500 LT and maximum tem-
perature for each day of the year, using hourly data from
the Que´bec City airport from 1970–2000. The 0800 and
1500 LT temperatures were chosen to allow a maximum
lag between the minimum/maximum and the hour of
observation, and to take into account the difference be-
tween solar time (by which Gaultier would have reck-
oned) and standard time, upon which the modern ob-
servations are based. Even with this adjustment, the
minimum temperatures were generally high, being close
to one standard deviation above the modern mean min-
imum temperature, especially in winter.
Almost no information is given as to the placement
of Gaultier’s thermometer, except that it was placed with
a north and northwest exposure, these being the direc-
tions of the coldest winds (Gaultier 1748). Given the
practices of the time (e.g., Manley 1953, 1962; Wilson
1983; Legrand and LeGoff 1992; Chenoweth 1993;
Slonosky et al. 2001b), it seems likely that the ther-
mometer was either hung on an outside wall of Gaul-
tier’s house, or placed near a window of an unheated
room. As the thermometer regularly gave readings be-
low 2208C, and as the socioeconomic conditions of life
in New France made the luxury of an unused room
. 2. Daily temperature values for (a) morning observations, taken between 0700 and 0800
LT, and (b) afternoon observations, taken between 1400 and 1500 LT, converted to 8C, for 1742–
48 and 1754, shown with the daily avg modern (1895–1995) mean min temperature 61
lines) and 62
(dotted lines) in (a), and the daily avg modern (1895–1995) mean max temperature
(solid line) and 62
(dotted lines) in (b).
. 3. As in Fig. 2 but for (a) the estimated min temperature, and (b) the estimated max
temperature, 1742–48 and 1754.
16JOURNAL OF CLIMATE
1. Estimates of length of frost-free season from 1743 to
1754, from weather descriptions and minimum temperature instru-
Estimates of frost-free season from
5 May–10 Sep
3 May–11 Sep
22 Apr–27 Sep
24 Apr–24 Sep
5 May–30 Aug
5 May–12 Oct
21 Apr–25 Sep
29 Apr–25 Sep
21 Apr–5 Oct
3 May–25 Oct
9 May–29 Oct
* Data ends in Sep 1748, before ﬁrst frost.
improbable (with such cold temperatures, it would be
impossible to carry out any daily tasks in an unheated
room in winter, or even to record the temperature read-
ings, as water and ink would have frozen solid), ex-
posure on an outside north-facing wall, probably outside
a window where the thermometer readings would be
visible from the inside, seems to be the most likely
exposure to the author. According to Wilson (1983),
Chenoweth (1993), and Parker (1994), the unscreened
north-wall exposure may lead to biases due to exposure,
ventilation, and heat retention by the building. Parker
(1994) concluded that north-wall exposures led an en-
hanced diurnal cycle compared to the observations taken
within a Stevenson screen, but the differences between
a standard Stevenson screen and a north-wall exposure
are very site-dependent. Biases for a north-wall expo-
sure estimated by the detailed studies of Wilson (1983)
and Chenoweth (1993) due to ventilation and exposure
to shortwave radiation are based on relatively short stud-
ies, some only a few months long, and range between
0.58 and 2.68C for the minimum temperature and from
08 to 21.98C for the maximum temperature(Chenoweth
1993), the overall bias for monthly mean temperature
ranging from 0.28 to 0.68C (Wilson 1983).
For Gaultier’s readings, given the lack of information
concerning the building, the degree of urbanization of
the site and the probable exposure to shortwave radia-
tion, it is the author’s considered opinion that the most
serious problem is likely to have been thermal lag in
the transfer of heat from the house (when heated) to the
thermometer, as the difference between the indoor and
outdoor temperature is likely to have been at least 258C
on the coldest winter days, for the socioeconomic rea-
sons outlined earlier. It is assumed the indoor temper-
ature would have to be, at the minimum, near zero, and
as we have seen, Gaultier’s thermometer regularly went
down to at least 2238C. This effect would be most
important for the coldest observations, those of winter
mornings. Accordingly, additional adjustment factors
were determined by adjusting the minimum values to
ﬁt with the weather descriptions given by Gaultier. This
was done by ensuring that when Gaultier described frost
or snow, the minimum temperature was at least 08C,
and conversely, if the day was described as frost-free,
ensuring the minimum value was above 08C. The ad-
justments determined for the minimum temperatures
were 0.58C for 1–15 April and 15 September–1 October,
18C for 15–31 March and 1–15 October, 1.58C from 1–
15 March and 15–31 October, and 28C from 1 Novem-
ber–15 March. No additional adjustments were applied
during the summer months as it is assumed the house
would not have been heated, and the maximum tem-
peratures are unaffected. All these adjustment factors
were ﬁltered using a 20-point Gaussian ﬁlter to provide
a smoothed annual cycle in the adjustment factors.
A check on these estimated values was made by com-
paring the length of the frost-free season as determined
by Gaultier’s weather descriptions to the length of the
frost-free season deﬁned by the number of days between
the last frost (last day with a minimum temperature at
or below 08C) in spring and the ﬁrst frost in autumn;
these are shown in Table 1.
The only major discrepancy is in 1745, when Gaultier
describes an unusual frost having occurred during the
night in late August but with a minimum temperature
still above 08C (Gaultier 1745); this is possible if strong
radiative cooling occurred near the ground, but the air
temperature a meter or so above the ground was still
above freezing. It is also possible that Gaultier is re-
porting frostlike damage, rather than a ‘‘killing frost’’
associated with below-zero temperatures (C. Mock
2002, personal communication), and so this early frost
date was left as anomalous. The next frost day described
by Gaultier in 1745 coincides well with the date of the
ﬁrst below-zero minimum temperature.
3. Warm summers, variable winters: Descriptions
of the climate of the 1740s
It is always difﬁcult to judge weather descriptions, as
they are subjective measures and depend on the ob-
server’s personal prior experience of weather and climate.
As a newcomer to the colony from France, Gaultier’s
perceptions of the weather extremes may be exaggerated,
although he himself was aware of this possibility and
took care to also record the remarks of inhabitants who
were born in the colony. Even these may be ﬂawed,
however, and so more objective descriptions, such as the
state of the snow cover, the arrival of migratory birds or
the appearance of rare species and the dates of harvest
of various fruits and grains are important ‘‘independent’’
descriptors. Gaultier’s detailed descriptions are given in
the following paragraphs, and a summary of the seasons
for 1742–47 is given in Table 2.
Although there are no instrumental observations be-
fore November 1742, the summer of 1742 was described
2. Summary of descriptions of seasons.
Year Winter Spring Summer Autumn
Very hot, dry
as very hot and dry. In January 1743, there were suf-
ﬁcient caribou near Que´bec City to form a caribou hunt;
this was a rare occurrence according to Gaultier, as only
in exceptionally cold winters did caribou migrate as far
south as Que´bec City. By February 1743, there were 8–
10 m (25–30 French ft) of snow and snow drifts in some
places. The summer of 1743 was hot during June and
An ice storm on 22 and 23 December 1743 left 8 cm
(3 French in.) of ice on the roofs and walls of houses.
A warm spell in the middle of January 1744 prompted
buds to appear on some trees, but this was followed by
a very cold spell ‘‘the worst in living memory; in less
than 10 minutes, nose, ears and lips froze, eyelids froze
shut and it was very painful to be outside’’ (Duhamel
du Monceau 1745). These alternating warm and cold
spells, with associated freeze–thaw cycles, continued
through February. The rest of the spring continued mild,
and the sowing was ﬁnished by May 11, one month
earlier than in 1743. The summer of 1744 was favorable
for agriculture, with fair weather throughout the sum-
A warm spell in November provided a brief return
to summerlike conditions, with the ﬁelds still green, and
the weather ‘‘inﬁnitely nicer than usual for the season’’
(Gaultier 1745). By 17 December, however, it had be-
come sufﬁciently cold that the nearby St. Charles River
had an ice cover thick enough to sustain the weight of
all kinds of vehicles. By March, the winter was con-
sidered to be the ‘‘mildest in living memory’’ (Gaultier
1745). June 1745 was described as an ‘‘extremely hot
month,’’ although the strawberry harvest was not ripe
until 22 June, 10 days later than in 1744. Gaultier de-
scribes June and July of 1745 as ‘‘excessively hot, but
with cool nights . . . and the countryside beautiful and
merry’’ (Gaultier 1745). By the end of August, however,
the temperature had cooled down to the point of hoar
frost on 30 and 31 August (although this is not reﬂected
in the temperature measurements).
November and December 1745 were mild. It froze
hard during the middle of December, but another warm
spell at the end of December melted most of the river
ice near the edge of the St. Lawrence River. The weather
remained very variable, with alternating cold and warm
spells; some days the temperature was above freezing,
others it was so cold the mercury condensed into the
bulb of the thermometer (i.e., colder than 2238C).These
occasional hard frosts but frequent thaws led Gaultier
to remark that ‘‘for Canada, it is very mild’’ (Duhamel
du Monceau 1747). By March, it was stated once again,
for the second year running, that ‘‘the oldest inhabitants
of the colony don’t remember such a mild winter, so
mild that the St. Lawrence didn’t even freeze over at
Que´bec.’’ July and August 1746 are described as very
hot, with so little rain that the rivers, wells, and other
water sources dried up, and the leaves began to wither
on the trees.
e. Winter 1746/47
A brief description of 1746/47 is found at the begin-
ning of the notes of 1747, and reads as follows:
‘‘The winter of 1747 was terrible, long and bitterly
cold. All the lakes, rivers and even the St. Lawrence
froze thick, so that carts and sleds could pass over. There
was a bridge of ice on the St. Lawrence all the way to
Montreal. The spring and summer were favourable for
vegetation, the snowmelt started early. The summer was
hot; this excessive heat made the crops grow quickly,
but the heat was tempered by rain storms. The heat
scorched the wheat and destroyed the harvest in a few
areas. In general, however, 1747 was very abundant for
all kinds of production.’’ (Gaultier 1748).
December of 1747 was very cold, and by the end of
December the river ice was thick enough to bear loaded
carts everywhere but on the southern edge of the St.
Lawrence River. January brought severe cold weather
and harsh blowing snow, which made it impossible to
go out even on sunny days. Gaultier estimated that 130
cm (4 French ft) of snow fell in January, and the rough
weather continued in February and March. June 1748
was hot, with such great heat that many plants and leaves
dried out in the heat. The ﬁrst half of July was exces-
sively hot; ‘‘perhaps such great heat has never been felt
before in Canada’’ (Gaultier 1748). The weather cooled
off to such an extent that ice patches were seen on 20
4. Climate change? A comparison with modern
a. Temperature and frost days
From Figs. 2 and 3 the winter of 1742/43 is seen to
have been cold. The winter of 1747/48 was also rela-
16JOURNAL OF CLIMATE
. 4. Monthly mean morning (1742–54) and 0800 LT (1960–2000) temperatures for (a) Jan,
(b) Feb, (c) Mar, (d) Apr, (e) May, (f) Jun, (g) Jul, (h) Aug, (i) Sep, (j) Oct, (k) Nov, and (l)
tively cold, and 1746/47, although no thermometer read-
ings have been located, was described as a ‘‘terrible
winter, both for the degree of cold and its length’’(Gaul-
tier 1748). Even with the adjustment factors described
in section 2, the summers appear to have been somewhat
warmer, on the whole, than the average over the past
century. Occasional comments as to the state of the
harvest or other agricultural phenomena tend to conﬁrm
the warmer, or possibly drier, summers: in June 1744,
the strawberry crop was ripe by 12 June (in modern
times, the strawberry crop of Que´bec City is often not
ripe until the end of June or beginning of July at the
earliest; mid to late July is more common), and in 1743
the heat caused the apples to fall off the trees prema-
turely in July. With such a small sample, it is impossible
to tell if this is evidence of a climatic change or normal
interannual variability. However, both the written de-
scriptions, the instrumental data and the phenomeno-
logical descriptions point to relatively warm summers
and variable winters; the winters of 1742/43 and 1746/
47 were both cold, but the winters of 1744/45 and 1745/
46 were mild, with frequent thaws and warm spells
throughout the winter. Winterseems to havestartedlater,
with mild autumns, but to have continued longer into
the spring, with snow a common occurrence as late as
May. The t tests show signiﬁcantly warmer Januarys
and cooler Mays in Gaultier’s records compared to the
1970–2000 period (see appendix Table A1).
Monthly means of the morning (Fig. 4) and afternoon
(Fig. 5) temperatures were calculated and compared to
the monthly mean 0800 (Fig. 4) and 1500 LT (Fig. 5)
temperatures for 1970–2000.
The morning temperatures for 1742–54 cluster near
the same values as for the modern period, although in
winter and autumn they tend to be nearer the upper
values of the modern period; January of 1754 is warmer
than any during the 1970–2000 period. The springs of
1742–54 were cooler than during the modern period,
especially March 1748 and April of 1742 and 1745,
suggesting that the winters lasted longer, even if they
were not as cold. The summers were quite variable, with
June of 1748 being colder than any of the past 30 yr,
but August of 1744 warmer than any of modern times.
The 1500 LT temperatures are somewhat higher than
during modern times, especially in autumn and winter
but as has been noted in section 2, there is a bias against
colder days, as the afternoon temperatures seem to have
been recorded when the weather was unusually mild for
the time of year, especially in winter. The summer
monthly afternoon temperatures of 1743–54 fall within
the general range of those for 1970–2000; although July
of 1748 stands out as being exceptionally hot.
The number of frost days, or days when the temper-
ature went below zero, was determined for each month
from Gaultier’s weather descriptions, and are shown in
Fig. 6. These agree well with the tendencies seen in the
minimum temperatures; the winters of the 1740s had
fewer frost days than in modern times, and Gaultier
describes several of the winters having pronounced
freeze–thaw cycles, a characteristic of modern winters
. 5. As in Fig. 4 but for monthly mean afternoon (1742–54) and 1500 LT (1960–2000)
. 6. As in Fig. 4 but for the number of frost days.
in Montreal, some 250 km to the southwest of Que´bec
City. The months from October to May have fewer frost
days during Gaultier’s period than during 1960–95,
those of November, April, and May having signiﬁcantly
fewer, as determined using t tests (see appendix Table
Although the only measurements taken by Gaultier
were the readings of his thermometer, he kept detailed
descriptions of each day’s weather, and from these it is
possible to obtain a number of counts: the number of
16JOURNAL OF CLIMATE
. 7. As in Fig. 4 but for rain (open circles) and snow (asterisks).
days each month with rain, snow, fog, hail, thunder,
freezing rain, blowing snow, frost, and snow on ground.
Many of these are also available for Que´bec City for
the 1960–95 period (Mekis and Hogg 1999).
A comparison of these climate indicators shows that
for almost all counts relating to precipitation, the num-
ber of days with precipitation-related events, including
rain, snow, and fog, was signiﬁcantly lower for all
months during the 1740s than during 1960–95 (Fig. 7).
Some of this deﬁciency may be due to underreporting
by Gaultier. Gaultier is unlikely to have noticed trace
precipitation events during the night, and may not have
recorded all trace or light-precipitation events during
the day, despite his frequent recordings of ‘‘petitepluie’’
(small rain). As trace events were not counted as pre-
cipitation days in the modern data (E. Mekis 2001, per-
sonal communication), this possible deﬁciency is not
likely to be larger than the difference observed between
the two periods. The possible differences in observing
measures and methods of counting precipitation days
make any conclusions about changes in precipitation-
day frequencies less robust.
With these limitations in mind, the precipitation-day
counts do indicate less precipitation, both rain and snow,
during the 1740s and 1754. The t tests (see appendix
Table A2) show these differences to be signiﬁcant for
all months. There are also statistically signiﬁcant fewer
fog days for all months in the 1740s and 1754, fewer
days with snow on ground for all months from Decem-
ber to April, fewer days with freezing rain for all months
from November to April, and fewer days on whichthun-
der was heard for all months from April to September
(see appendix Table A2). The ratio of rain to snow was
slightly higher in the 1740s and 1754 for January and
February, but lower in the other months. As more pre-
cipitation fell as rain in January and February, this
would indicate warmer winters, but as the reverse is true
for the other months, notably spring and autumn, this
is a further indication that the other seasons wereslightly
cooler, with more snow than in modern times.
By far the most prominent wind directions recorded
were southwest (48.5%) and northeast (34.4%), reﬂect-
ing the orientation of the St. Lawrence valley (Table 3).
The St. Lawrence valley lies between the Appalachian
highlands to the south and the Laurentian highlands to
the north. The orography of these higher-elevation areas
and the St. Lawrence lowlands is sufﬁcient to channel
the wind ﬂow of southern Que´bec in a predominantly
southwest to northeast direction. The weather systems
and storms tracks of this region tend to track up the St.
Lawrence River towards the Gulf of St. Lawrence and
Newfoundland to the northeast, before heading across
the Atlantic toward the Icelandic low. The dominance
of winds from the southwest and northeast is partly an
effect of this funnelling of the ﬂow through the St. Lawr-
ence valley (Powe 1968). The next most common wind
direction is northwest (11.2%), and is the one Gaultier
associates with the coldest weather, attributing this to
‘‘the winds [from the north and northwest] which pass
3. Percentage of wind direction (Dir.) frequency.
Dir. Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec All
over Hudson’s Bay and over some mountains [the Lau-
rentians] which are always covered in snow and ice, and
always have been.’’ (Gaultier 1748). This was a mis-
perception on the part of Gaultier; evidence from the
Hudson’s Bay Company archives (Catchpole et al. 1976;
Ball 1992) indicates that Hudson’s Bay and the Lau-
rentians were not perpetually covered in snow and ice
in the eighteenth century, and they are certainly snow-
and ice-free during the summer months in modern times.
There are very few winds recorded from other direc-
d. Seasonal means and interannual variability
Figure 8 shows the seasonal means and standard de-
viations of Gaultier’s observations, compared to 6-yr
running means and standard deviations for the period
1895–1995 at Que´bec. (All series are shown for the
minimum temperature.) From Fig. 8a, it can be seen that
the winter average temperature during this brief period
was indeed warm relative to the twentieth century; only
the winters of the 1950s and the early 1980s were as
warm or warmer than the 1740s. The winters of the late
1980s and 1990s were cooler. The summers were also
warm relative to the twentieth century, with only the
1970s and the 1990s showing summer conditions as
warm as or warmer than the 1740s. The springs and
autumns, on the other hand, are cool relative to the
twentieth century, and were colder than springs and au-
tumns have been since the 1950s. As has been discussed
earlier, the winter season, while milder, may have been
prolonged through cooler autumns and springs. The in-
terannual variability, as seen from the few years of Gaul-
tier’s observations and the 6-yr running means during
the twentieth century, has remained largely the same,
except for a slightly lower interannual variability during
the autumns of the 1740s.
5. Discussion and conclusions
Assessing the quality of the data is always a problem
when using historical data, especially if little is known
about the instruments and their exposure. While there
are few, if any, published paleoclimatic series of suf-
ﬁcient temporal resolution in the St. Lawrence valley
region with which it is possible to directly compare
Gaultier’s data, there exist several studies of historical
documentary data and paleoclimatic data from eastern
and northern North America. Evidence from documen-
tary sources from the Hudson’s Bay Company archives
indicate that the autumns of the 1740s near southern
James Bay were warmer, with a later date of river freeze-
up than during the nineteenth century, and that the
springs were cool, with a later date of river ice breakup
in the spring (Catchpole et al. 1992). From the Hudson’s
Bay Company archive data, 1743/44 is classiﬁed as a
very mild winter at both Churchill (on the westernshore
of Hudson’s Bay) and at York Factory (on the south-
western shore of James Bay); 1740/41, 1747/48, and
1748/49 are classiﬁed as severe in both places (Ball
1992); which agrees with Gauthier’s descriptive obser-
vations at Que´bec City as far as 1747/48 is concerned
(Gaultier 1748). Gaultier’s very mild winter of 1745/46
and very cold winter of 1746/47 do not seem to have
been remarkable further north and west. There are no
meteorological observations available at Que´bec City
for the winter of 1746/47, and the perception of cold
may have been slightly exaggerated in comparison with
the mild winters of the previous few years. These doc-
umentary data from the Hudson’s Bay Company also
indicate that the 1740s, 1750s, and 1760s were dry at
York Factory (Ball 1992). Documentary data from New
England, in the northeastern United States, also indicate
the 1740s were dry, particularly during the growing sea-
son (Baron 1992). Analysis of the frost-free season for
New England shows that the 1740s were the most var-
iable decade of the last 250 years in terms of the number
of frost-free days (Baron et al. 1984).
Dendroclimatic observations also show that the sum-
mers of the 1740s were relatively warm and dry; tree-
ring composites over the entire northern North America
indicate that the 1740s were as warm as the 1950s
(d’Arrigo and Jacoby 1992). D’Arrigo et al. (1999) de-
scribe similar results for annual temperature over the
Northern Hemisphere; the 1730s and 1750s were warm,
as warm as the 1951–80 period, while the 1740s were
slightly cooler. The year 1740 is recognized as being
one of the coldest in Europe in over 300 years (Luter-
16JOURNAL OF CLIMATE
. 8. The 6-yr running means of seasonal mean temperature for 1895–1995 (solid line),
(dotted lines), as well as mean seasonal temperature for 1742/43–1745/46 (diamond),
(triangles); 1742/43–1747/48 (circle), 61
(asterisk); and 1742/43 to 1754 (square), 61
(plus sign) for: (a) winter, (b) spring, (c) summer and (d) autumn.
bacher et al. 2002), and both 1740 and 1742 rank among
the 30 coldest Northern Hemisphere summers of the past
600 years, based on tree-ring data (Briffa et al. 1998),
in contrast to Gaultier’s description of 1742 as a warm
summer. Tree-ring evidence from northern Que´bec and
the Hudson’s Bay region shows that this was a period
of general warmth between two severe phases of the
Little Ice Age in eastern North America, the ﬁrst during
the late seventeenth century and the second after 1815
(Guiot 1985; Scott et al. 1988; S. Payette 2001, personal
communication). Borehole evidence of annual average
temperature also suggests that the Little Ice Age cold
signal near the Que´bec City region and Atlantic Canada
is less pronounced than elsewhere in eastern and central
Canada (Beltrami 1992). Warm sea surface temperatures
in the Labrador Sea during the Little Ice Age period
(Keigwin and Pickart 1999) may also have led to warm-
er conditions in Atlantic Canada and possibly also Que´-
bec. Tree-ring reconstructions of precipitation in the
eastern United States also indicate the 1740s were dry
in the regions bordering on the province of Que´bec
(Cook et al. 1992). Overpeck et al. (1997) found that
many Arctic sites were warmer during the 1700–1820
period than during the nineteenth century, while further
west, glacial evidence from the Rockies show that the
most extensive glacial advances of the Holocene were
during the eighteenth and nineteenth centuries, and tree-
ring densities suggest that the early eighteenth century
was particularly cold (Luckman 1996).
Gaultier’s instrumental and descriptive observations
show that the climate of these few years of 1742–48
and 1754 appear to fall within the generally expected
range of climate variability for the twentieth century.
There are some indications that the winters in particular
were milder, from the temperature observations, the
number of frost days, and the ratio of rain to snow.
However, it is difﬁcult to assess how well these few
years of data reﬂect the climate of the decade. One
winter for which the instrumental observations are lost
(1746/47) was described as extremely harsh, and Gaul-
tier describes the mild winters as unusual, and the hot
summer of 1748 as ‘‘possibly the warmest ever in Can-
ada’’ (Gaultier 1748). These comments suggest that the
warmth of these years may have been unusual.
The counts of rain and snow days are also much below
the modern period. While some portion of these low
values may be due to underreporting and other uncer-
tainties in Gaultier’s observations, it seems likely, based
on the supplementary phenological observations sum-
marized in section 3 and by the historical and paleo-
climatic studies cited in the previous paragraph, that
some part of these low counts are due to an actual re-
duction in precipitation. Studies of historical data in
France point to the 1740s as being a dry period, and
show a consistent upward trend in precipitation from
the seventeenth century to the present (Slonosky 2002).
Northern Hemisphere precipitation data of the twentieth
century indicate an increase over the mid and high lat-
itudes of the Northern Hemisphere of a rate on the order
of 7%–12% century
(Folland et al. 2001). Several
authors have commented on the more continental cli-
mate of the seventeenth and eighteenth centuries in Eu-
rope, compared to a milder, more maritime climate in
the twentieth century, based on instrumental (Jacobeit
et al. 2001) and documentary (Ogilvie and Jo´nsson
2001) historical data.
From the evidence of milder, or at least more variable,
winters and reduced precipitation, it may be possible to
infer some changes in the atmospheric circulation. It
seems likely that there was increased meridional ﬂow
in winter, as the descriptions of intense cold alternating
with thaws are characteristic of winters with increased
meridional ﬂow in this area, bringing alternating sub-
tropical and polar air masses into the region. Recon-
structions of the NAO by Luterbacher et al. (1999, 2002)
show the NAO to have been low or negative (indicating
meridional ﬂow) from 1740 to 1742, mostly positive
(indicating westerly ﬂow) during 1743 and 1744 and
then mostly low or negative again from 1745 until the
summer of 1748. Jo¨nsson and Fortuniak (1995) reported
higher frequencies of easterly winds for northwestern
Europe during the 1740s, and the proxy reconstruction
of the NAO by Cook et al. (1998) also indicate generally
low values of the NAO during the 1740s. The model
study of Shindell et al. (2001) shows an increase of
0.348C in global average temperatures between 1680
and 1780 based upon model results simulating the ex-
pected climate change due to changes in insolation and
the modeled changes in atmospheric circulation, partic-
ularly the Arctic Oscillation (AO, similar in concept to
the NAO in that it represents an important mode of
atmospheric variability over the Northern Hemisphere
and is positively linked to the strength of the zonal ﬂow)
during the 1680–1760 period; the 1740s fall in the mid-
dle of this modeled transition to more zonal circulation
and warming over parts of eastern North America. How-
ever, neither the NAO nor the AO have any correlation
with temperature over southern Que´bec, at least in mod-
ern times (Hurrell 1996; Thompson and Wallace 1998;
Slonosky and Yiou 2002), although the NAO recon-
structions do provide some indications as to the strength
of the westerlies, albeit farther east, over the North At-
lantic/European sector. The temperature observations
are also consistent with the possibility that the winter
polar jet stream was positioned farther north, allowing
Que´bec City to come under the inﬂuence of warm sub-
tropical air masses more frequently; this would also ac-
count for the more pronounced winter freeze–thaw cy-
cles, although not for the reduced precipitation. Hot and
dry summers are also characteristic of increased merid-
ional and blocking ﬂow, with fewer large-scale cyclones
passing regularly through the region from the Great
Lakes to the Atlantic Ocean.
These early instrumental data from Que´bec City add
to the growing picture of complex spatial and temporal
climatic variability on regional scales during the Little
Ice Age. The seventeenth century is classiﬁed as the
coldest century of the past millennium over the Northern
Hemisphere, followed by the nineteenth century (Jones
1998). From Northern Hemisphere temperature recon-
structions, the eighteenth century appears to have been
milder, although still cooler than the twentieth (Jones
1998; Jones et al. 2001). In this region, parts of the
eighteenth century were as warm as some of the warmest
years of the twentieth, at least for the winter and summer
seasons. The spring and autumn seasons were cold rel-
ative to twentieth century averages, bringing the annual
average temperatures of these years of the 1740s down
to near the annual average of the twentieth century. All
seasons were signiﬁcantly drier than the twentieth cen-
tury. It is clear that this period of the Little Ice Age in
eastern North America was not one of uniform coldness,
and that considerable interannual variability existeddur-
ing this period.
These early observations are of great importance, as
they are among the ﬁrst instrumental meteorological re-
cords from North America, and so can provide a window
on the climate and climatic variability at a daily reso-
lution for this site in eastern North America. Other ar-
chival instrumental records are also available for the St.
Lawrence valley, covering most of the nineteenth cen-
tury, which may be able to provide longer-term records,
also at a monthly or daily resolution, of climate change
and variability in this region. These records, like all
reliable historical instrumental records, are of vital im-
portance to the understanding of climate variability and
change on decadal to century timescales, as well as to
placing in context the climatic changes of the past few
decades. Every effort should be made to ensure that
these data are not lost, and that their potential be re-
Acknowledgments. Many thanks are due to the li-
brarians and archivists of l’Observatoire de Paris and
to Thomas Wien for their help and advice on the man-
uscripts of Jean-Franc¸ois Gaultier. The meteorological
data for 1754 were obtained from the Houghton Library,
Harvard University. The author is grateful to Lucie Vin-
va Mekis, Xuebin Zhang, Francis Zwiers, and
Jacques Derome for many interesting discussions. Lucie
Vincent and E
va Mekis provided the twentieth century
temperature and precipitation data for Que´bec City. The
apt and insightful comments of Mike Mann, Cary Mock,
and Daniel Druckenbrod have considerably improved
Changing Climate: Differences between Eighteenth-
and Twentieth-Century Que´bec City Climate
The following tables compare climate data for 1742–
54 and the late twentieth century.
16JOURNAL OF CLIMATE
A1. Monthly mean and std dev of morning (0800) and afternoon (1500 LT) temperature at Que´bec City for 1742–54 and 1970–
2000, with t statistic values of the differences between the two periods.
Element Jan Feb Mar Apr
Morning temperature Mean 1742–54
Std dev 1742–54
Std dev 1970–2000
Afternoon temperature Mean 1742–54
Std dev 1742–54
Std dev 1970–2000
* The t value denotes difference statistically signiﬁcant at 95% level.
A2. Monthly mean and std dev of number of days of rain, snow, precipitation, freezing rain, fog, hail, thunder, and frost at
Que´bec City for 1742–54 and 1960–95, with t statistic values of the differences between the two periods.
Element Jan Feb Mar Apr
Rain Mean 1742–54
Std dev 1742–54
Std dev 1960–95
Snow Mean 1742–54
Std dev 1742–54
Std dev 1960–95
Precipitation Mean 1742–54
Std dev 1742–54
Std dev 1960–95
Freezing rain Mean 1742–54
Std dev 1742–54
Std dev 1960–95
Fog Mean 1742–54
Std dev 1742–54
Std dev 1960–95
Hail Mean 1742–54
Std dev 1742–54
Std dev 1960–95
t value 21.0 0.0 21.0 21.4
Thunder Mean 1742–54
Std dev 1742–54
Std dev 1960–95
Frost Mean 1742–54
Std dev 1742–54
Std dev 1960–95
* The t value denotes difference is statistically signiﬁcant at 95% level.
May Jun Jul Aug Sep Oct Nov Dec
May Jun Jul Aug Sep Oct Nov Dec
20.2 0.2 20.2 22.1 0.5 21.8 21.0 0.0
16JOURNAL OF CLIMATE
Auer, I., R. Bo¨hm, and W. Scho¨ner, 2001: Long climatic series from
Austria. History and Climate: Memories of the Future? P. D.
Jones et al., Eds., Kluwer Academic Press, 125–151.
Ball, T. F., 1992: Historical and instrumental evidence of climate:
Western Hudson Bay, Canada, 1714–1850. Climate Since A.D.
1500, R. S. Bradley and P. D. Jones, Eds., Routledge, 40–73.
Baron, W. R., 1992: Historical climate records from the northeastern
United States, 1640 to 1900. Climate Since A.D. 1500, R. S.
Bradley and P. D. Jones, Eds., Routledge, 74–91.
——, G. S. Gordon, H. W. Borns, and D. C. Smith, 1984: Frost-free
reconstruction for eastern Massachusetts, 1733–1980. J. Climate
Appl. Meteor., 23, 317–319.
Beltrami, H., 1992: Ground temperature histories for central and east-
ern Canada from geothermal measurements: Little Ice Age sig-
nature. Geophys. Res. Lett., 19, 689–692.
Briffa, K., P. D. Jones, F. H. Schweingruber, and T. J. Osborn, 1998:
Inﬂuence of volcanic eruptions on Northern Hemisphere summer
temperature over the past 600 years. Nature, 393, 450–455.
Catchpole, A. J. W., 1992: Hudson’s Bay Company ships’ logbooks
as sources of sea-ice data, 1751–1870. Climate Since A.D. 1500,
R. S. Bradley and P. D. Jones, Eds., Routledge, 17–39.
——, D. W. Moodie, and D. Milton, 1976: Freeze-up and break-up
of estuaries on Hudson Bay in the 18th and 19th centuries. Can.
Geogr., 20, 279–297.
Chenoweth, M., 1993: Nonstandard thermometer exposures at U.S.
cooperative weather stations during the late nineteenth century.
J. Climate, 6, 1787–1797.
Cook, E. R., D. W. Stahle, and M. K. Cleaveland, 1992: Dendrocli-
matic evidence from eastern North America. Climate Since A.D.
1500, R. S. Bradley and P. D. Jones, Eds., Routledge, 331–348.
——, R. D. d’Arrigo, and K. R. Briffa, 1998: A reconstruction of
the North Atlantic Oscillation using tree-ring chronologies from
North America and Europe. Holocene, 8, 9–17.
Crowley, T. J., 2000: Causes of climate change over the past 1000
years. Science, 289, 270–277.
d’Arrigo, R. D., and G. C. Jacoby, 1992: Dendroclimatic evidence
from northern North America. Climate Since A.D. 1500, R. S.
Bradley and P. D. Jones, Eds., Routledge, 296–311.
——, G. Jacoby, M. Free, and A. Robock, 1999: Northern Hemi-
sphere temperature variability for the last three centuries: Tree-
ring and model estimates. Climatic Change, 42, 663–675.
Demare´e, G. R., and A. E. J. Ogilvie, 2001: Bons baisers d’Islande:
Climatic, environmental and human dimensions impacts of the
Lakagı´gar eruption (1783–1784) in Iceland. History and Cli-
mate: Memories of the Future? P. D. Jones et al., Eds., Kluwer
Academic Press, 219–246.
Duhamel du Monceau, H. L., 1744: Observations botanico–me´te´o-
rologiques faites a` Que´bec par M. Gaultier pendant l’anne´e 1743.
Me´m. Acad. Roy. Sci., 1744, 135–155.
——, 1745: Observations botanico–me´te´orologiques faites a` Que´bec
par M. Gaultier pendant l’anne´e 1744. Me´m. Acad. Roy. Sci.,
——, 1746: Observations botanico–me´te´orologiques faites a` Que´bec
par M. Gaultier pendant l’anne´e 1745. Me´m. Acad. Roy. Sci.,
——, 1747: Observations botanico–me´te´orologiques faites a` Que´bec
par M. Gaultier pendant l’anne´e 1746. Me´m. Acad. Roy. Sci.,
Folland, C. K., and Coauthors, 2001: Observed climate variability
and change. Climate Change 2001: The Scientiﬁc Basis, J. T.
Houghton et al., Eds., Cambridge University Press, 100–181.
Gaultier, J.-F., 1745: Journal des observations me´te´orologiques de M.
Gaultier a` Kebec. Observatoire de Paris Manuscript, Doc. No.
64-5-B, 103 pp. [Available from Fonds Joseph-Nicolas Delisle,
Observatoire de Paris, 61 Avenue de l’observatoire, Paris 75014,
——, 1748: Journal des observations me´te´orologiques de M. Gaultier
a` Kebec depuis le 1 octobre 1747 jusqu’au 1 octobre 1748.
Observatoire de Paris Manuscript, Doc. No. 64-6-A, 71 pp.
[Available from Fonds Joseph-Nicolas Delisle, Observatoire de
Paris, 61 Avenue de l’Observatoire, Paris 75014, France.]
——, 1755: Journal des observations me´te´orologiques de M. Gaultier
a` Kebec 1754. Meteorological Collection, Houghton Library,
Doc. No. 57M-13, 17 pp. [Available from Houghton Library,
Harvard University, Cambridge, MA 02138.]
Grove, J. M., 2001: The onset of the Little Ice Age. History and
Climate: Memories of the Future? P. D. Jones et al., Eds., Kluwer
Academic Press, 153–185.
Guiot, J., 1985: Reconstruction of seasonal temperatures and sea-
level pressures in the Hudson Bay area back to 1700. Climatol.
Bull., 19, 11–59.
Harrington, C. R., Ed.,1992: The Year without a Summer? World
Climate in 1816. Canadian Museum of Nature, 576 pp.
Hurrell, J. W., 1996: Inﬂuence of variations in extratropical winter-
time teleconnections on Northern Hemisphere temperature. Geo-
phys. Res. Lett., 23, 665–668.
Jacobeit, J., P. Jo¨nsson, L. Ba¨rring, C. Beck, and M. Ekstro¨m, 2001:
Zonal indices for Europe 1780–1995 and running correlations
with temperature. Climatic Change, 48, 219–241.
Jones, P. D., 1998: It was the best of times, it was the worst of times.
Science, 280, 544–545.
——, T. Jo´nsson, and D. Wheeler, 1997: Extension to the North
Atlantic Oscillation using early instrumental pressure observa-
tions from Gibraltar and south-west Iceland. Int. J. Climatol.,
——, M. New, D. E. Parker, S. Martin, and I. G. Rigor, 1999: Surface
air temperature and its changes over the past 150 years. Rev.
Geophys., 32, 173–199.
——, T. J. Osborn, and K. R. Briffa, 2001: The evolution of climate
over the last millenium. Science, 292, 662–666.
Jo¨nsson, P., and K. Fortuniak, 1995: Interdecadal variations of surface
wind direction in Lund, southern Sweden, 1741–1990. Int. J.
Climatol., 15, 447–461.
Jo´nsson, T., and H. GarUarsson, 2001: Early instrumental meteoro-
logical observations in Iceland. Climatic Change, 48, 169–187.
Keigwin, L. D., and R. S. Pickart, 1999. Slope water current over
the Laurentian Fan on interannual to millennial time scales. Sci-
ence, 286, 520–523.
Legrand, J.-P., and M. LeGoff, 1992: Les observations me´te´orolo-
giques de Louis Morin. Monographie No. 6, Direction de la
Me´te´orologie Nationale, Ministe`re de l’equipement, du logement
et des transports, 28 pp. and appendices.
Luckman, B., 1996: Reconciling the glacial and dendroclimatological
records for the ﬁrst millenium in the Canadian Rockies. Climatic
Variations and Forcing Mechanisms of the Last 2000 Years, P.
D. Jones et al., Eds., Springer-Verlag, 85–124.
Luterbacher, J., C. Schmutz, D. Gyalistras, E. Xoplaki, and H. Wan-
ner, 1999: Reconstruction of monthly NAO and EU indices back
to AD 1675. Geophys. Res. Lett., 26, 2745–2748.
——, and Coauthors, 2000: Reconstruction of monthly mean sea level
pressure over Europe for the Late Maunder Minimum period
(1675–1715) based on canonical correlation analysis. Int. J. Cli-
matol., 20, 1049–1066.
——, and Coauthors, 2002: Reconstruction of sea level pressure ﬁelds
over the eastern North Atlantic andEurope back to 1500. Climate
Dyn., 18, 545–561.
Manley, G., 1953: The mean temperature of central England, 1698–
1952. Quart. J. Roy. Meteor. Soc., 79, 242–261.
——, 1962: Early meteorological observations and the study of cli-
matic ﬂuctuations. Endeavour, 21, 43–51.
——, 1974: Central England temperatures: Monthly means 1659 to
1973. Quart. J. Roy. Meteor. Soc., 100, 389–405.
Mann, M. E., J. Park, and R. S. Bradley, 1995: Global interdecadal
and century-scale climate oscillations during the past ﬁve cen-
turies. Nature, 378, 266–270.
——, R. S. Bradley, and M. K. Hughes, 1998: Global-scale temper-
ature patterns and climate forcing over the past six centuries.
Nature, 392, 779–787.
Mekis, E., and W. D. Hogg, 1999: Rehabilitation and analysis of
Canadian daily precipitation time series. Atmos.–Ocean, 37, 53–
Middleton, W. E. K., 1966: A History of the Thermometer and Its
Use in Meteorology. Johns Hopkins Press, 249 pp.
Moberg, A., and Coauthors, 2000: Day-to-day temperature variability
trends in 160- to 274-year long European instrumental records.
J. Geophys. Res., 105, 22 849–22 868.
New, M., M. Hulme, and P. Jones, 2000: Representing twentieth
century space–time climate variability. Part II: Development of
1901–96 monthly grids of terrestrial surface climate. J. Climate,
Ogilvie, A., and T. Jo´nsson, 2001: ‘‘Little Ice Age’’ research: A
perspective from Iceland. Climatic Change, 48, 9–52.
Overpeck, J., and Coauthors, 1997: Arctic environmental change of
the last four centuries. Science, 278, 1251–1256.
Parker, D. E., 1994: Effects of changing exposure of thermometers
at land stations. Int. J. Climatol., 14, 1–31.
Pﬁster, C., J. Kington, G. Kleinlogel, H. Schu¨le, and E. Siffert, 1994:
High resolution spatio–temporal reconstructions of past climate
from direct meteorological observations and proxy data. Climatic
Trends and Anomalies in Europe 1675–1714, B. Frenzel et al.,
Eds., Fischer, 329–376.
Powe, N. N., 1968: The inﬂuence of a broad valley on the surface
winds within the valley. Dept. of Transport Tech. Note 668,
Toronto, Canada, 20 pp.
Scott, P. A., D. C. F. Fayle, C. V. Bentley, and R. I. C. Hansell, 1988:
Large-scale changes in atmospheric circulation interpreted from
patterns of tree growth at Churchill, Manitoba, Canada. Arct.
Alp. Res., 20, 199–211.
Shindell, D. T., G. A. Schmidt, M. E. Mann, D. Rind, and A. Waple,
2001: Solar forcing of regional climate change during the Maun-
der Minimum. Science, 294, 2149–2152.
Slonosky, V. C., 2002: Wet winters, dry summers? Three centuries
of precipitation data from Paris. Geophys. Res. Lett, 29 (19),
1895, doi: 10.1029/2001GL014302.
——, and P. Yiou, 2002: Changes in the inﬂuence of zonal circulation
and North Atlantic Oscillation on surface temperatures, 1856–
1998. Climate Dyn. 19, 17–30.
——, P. D. Jones, and T. D. Davies, 2001a: Circulation and temper-
ature relationships in Europe on decadal to century scales. Int.
J. Climatol., 21, 63–75.
——, ——, and ——, 2001b. Instrumental pressure observations and
atmospheric circulation from the 17th and 18th centuries: Lon-
don and Paris. Int. J. Climatol, 21, 285–298.
Thompson, D. W. J., and J. M. Wallace, 1998: The Arctic oscillation
signature in the wintertime geopotential height and temperature
ﬁelds. Geophys. Res. Lett., 25, 1297–1300.
Valle´e, A., 1930: Cinq lettres ine´dites de Jean-Franc¸ois Gaultier a`M.
de Rhe´amur de l’Academie des Sciences. Me´m. Comptes Ren-
dues Soc. Roy. Can., Series 3, 24, 31–43.
van Engelen, A. F. V., J. Buisman, and F. IJnsen, 2001: A millennium
of weather, winds and water in the Low Countries. History and
Climate: Memories of the Future? P. D. Jones et al., Eds., Kluwer
Academic Press, 101–124.
Vincent, L. A., X. Zhang, B. R. Bonsal, and W. D. Hogg, 2002:
Homogenization of daily temperatures over Canada. J. Climate,
Wien, T., 1990: ‘‘Les travaux pressants.’’ Calendrier agricole, asso-
lement et productivite´ au Canada au XVIIIe sie`cle. Rev. Hist.
Ame´r. Fr., 43, 535–558.
Wilson, C., 1983: Some aspects of the calibration of early Canadian
temperature records in the Hudson’s Bay Company archives: A
case study for the summer season, eastern Hudson/James Bay,
1814 to 1821. Climatic Change in Canada 3, C. R. Harrington,
Ed., Syllogeus Series, Vol. 49, National Museum of Natural Sci-
ences, National Museums of Canada, 144–219.