No place on earth has a climate as cold as Antarctica's. Average daily temperatures nearly everywhere are below freezing even during the warmest months (November to February), when the sun shines continuously on most of Antarctica. Winter temperatures are lowest on the polar plateau, where they average as low as -90° F. (-68° C.). A temperature of -128.6° F. (-89.2° C.), the world's record, was recorded in 1983 at the Soviet Union's Vostok base, about 800 miles (1,290 km) from the South Pole. Winter readings along the coast in some places average from -30° F. to -5° F. (-34° C. to - 21° C.). The warmest part of Antarctica is the northernmost fringes of the Antarctic Peninsula, where average summer temperatures are above freezing from one to four months of the year.

Snowfall is greatest near the relatively warm ocean, where yearly accumulations average the equivalent of 8 to 30 inches (200 to 760 mm) of rain, depending on location. Little snow falls in the dry interior. The average annual snowfall for the continent as a whole is equivalent to roughly 4 inches (100 mm) of rain.

Antarctic snow is very dry and powdery. It is whipped by fierce winds into blizzards longer and more intense than anywhere else in the world. These winds, sharpening the already bitter cold of the Antarctic, sometimes sweep down the slopes of the polar plateau at speeds up to 200 miles per hour (320 km/h), especially along the Adélie Coast. Windless days are rare.

Occasionally, low cloud layers cause a uniform white light to bounce back and forth between the clouds and the snow. In this eerie condition, known as whiteout, the horizon and all shadows vanish and a person can lose all sense of direction.