Skin disorders such as atopic dermatitis, psoriasis and senile xerosis show a tendency to exacerbate in winter. We investigated the seasonal influence on the functional parameters of the skin in healthy female volunteers of different age groups. Biophysical noninvasive measurements, including transepidermal water loss (TEWL) as a parameter for the barrier function of the stratum corneum (SC), high-frequency conductance as a parameter for the hydration state of the SC, temperature, color and casual surface lipid levels, were conducted during the later summer and winter months in 39 healthy adult Japanese females ranging in age from 24 to 78 years. The measurements were made on the cheek, the exposed area, and flexor forearm, the semicovered area, in the same climate-controlled chamber. The barrier function of the SC was found to be significantly impaired in winter both on the cheek and flexor forearm. This difference between summer and winter was much larger on the cheek than on the forearm. The hydration state of the SC was significantly lower in winter on the flexor forearm, whereas no such seasonal change was apparent on the cheek where sebum levels did not show any seasonal change. We measured the corneocyte size in 24 out of the 39 subjects to estimate a seasonal change of the turnover rate of the SC. It tended to be smaller only on the exposed cheek skin, suggesting an enhanced turnover of the SC in winter, whereas it was somewhat larger on the semicovered flexor forearm. The skin surface temperature and redness were also significantly higher on the cheek in winter. We think that subclinical inflammation resulted in the enhanced turnover rate of the SC associated with elevated TEWL levels observed on the face in winter. In conclusion, the obtained data suggest that the exposed facial skin becomes more irritable under the influence of the dry and cold environment of winter even in healthy individuals where the barrier function of the SC is relatively poor as compared to the skin of other areas.