Seasonal snow cover in South America was examined in this study using passive microwave satellite data from the Scanning Multichannel Microwave Radiometer (SMMR) on board the Nimbus-7 satellite, data from the Special Sensor Microwave Imagers (SSM/I) on board Defense Meteorological Satellite Program (DMSP) satellites and limited data from the Advanced Microwave Scanning Radiometer (AMSR) on board the Aqua satellite. For the period from 1979-2002, both snow cover extent and snow depth (snow mass) were investigated during the winter months (May-August) in the Patagonia region of Argentina. South America is the only continent in the Southern Hemisphere (other than Antarctica) where an extensive, non-mountainous, winter snow cover may occur. In southern Argentina, snow may accumulate as early as May and as late as October. Since above normal temperatures in this region are typically above freezing, the coldest winter month (usually July) was found to be not only the month having the most extensive snow cover but also the month having the deepest snows. For the 20 plus-year period of this study, the average snow cover extent (May-August) was approximately 4.50 million km² and the average monthly snow mass (May-August) was approximately 1.20 x 10¹³ kg.