The extent and duration of snow cover plays an important role in determining and modeling climate in mid to high latitudes. Snow cover affects climate in three key ways: (i) Snow has high reflectivity to short wave radiation, strongly affecting the surface energy balance. This tends to lead to cooler surface temperatures and a stabilization of the lower atmosphere. (ii) Snow cover acts to store energy on the surface in some seasons, but release it to the atmosphere and underlying ice during other seasons. (iii) Snow cover also acts to help thermally decouple the atmosphere and underlying surface due to its low thermal conductivity. This latter effect is especially important over sea ice, where the atmosphere is insulated from the underlying (warmer) ocean. The ability of the SNTHERM snow pack model to simulate this profile, and thereby improve the overall performance of global and regional climate models, has been assessed. This was accomplished by forcing SNTHERM with output from the NCAR CCM3 global model and NCAR/PSU RegCM2 regional climate model. The resulting snow cover was then compared with that simulated by the climate models using their own crude snow hydrologies. Testing was done over both land points and sea ice points. In almost every case, SNTHERM provided a better simulation of the seasonal cycle of snow cover. This improvement was especially obvious over sea ice, where the SNTHERM gave results in better agreement with observations.