Antarctica is the coldest place on Earth. At the 3 km high Vostok Station in Antarctica, scientists recorded Earth's lowest temperature: −89 °C. Sunburn is often a health issue as the snow surface reflects almost all of the ultraviolet light falling on it. Heavy snowfalls are not uncommon on the coastal portion of the continent, where snowfalls of up to 1.22 m in 48 hours have been recorded.

At the edge of the continent, strong katabatic winds off the polar plateau often blow at storm force. In the interior, however, wind speeds are typically moderate. During summer, more solar radiation reaches the surface during clear days at the South Pole than at the equator because of the 24 hours of sunlight each day at the Pole. Antarctica is warming as a result of human CO2 emissions.

About 98% of Antarctica is covered by the Antarctic ice sheet, a sheet of ice averaging at least 1.6 km thick. The continent has about 90% of the world's ice (and thereby about 70% of the world's fresh water). If all of this ice were melted, sea levels would rise about 60 metres. In most of the interior of the continent, precipitation is very low, down to 20 mm per year; in a few "blue ice" areas precipitation is lower than mass loss by sublimation and so the local mass balance is negative. In the dry valleys the same effect occurs over a rock base, leading to a desiccated landscape.