We present the effect of air ionization during and prior to large earthquakes. During and prior to large earthquakes, radon discharge from different cracks and faults is the primary source of air ionization. The newly formed ions coagulates with water molecules and drastic change in air temperature and relative humidity is observed. These changes extend up to the increment of surface latent heat flux also and can be observed though various remote sensing satellite as well as in many ground based measurements of surface air heat and other thermal parameters. We are presenting the change in air temperature, relative humidity and surface latent heat flux parameters as a precursory phenomenon of Nepal 2016 and Honsu 2011 Earthquakes. As the thermal excitation profile is different for land and sea, we compare the variation of pre-seismic thermal parameters for Nepal (land) and Honsu (near sea) earthquakes.