Climate of Antarctica

Three things make Antarctica so cold. The first is latitude: near the pole the sun stays low in the sky even in summer, and its light arrives spread out; in winter it disappears for weeks or months.

The second is altitude. Much of the plateau lies above 3,000 meters, and temperature falls with elevation. The third is the ice itself: white snow reflects most of the light it receives back into space.

The Southern Ocean and the Circumpolar Current help isolate the continent from the warmer air and water to the north. That is why the South Pole is much colder than the North Pole, which lies over an ice-covered ocean near sea level.

The lowest air temperature ever measured by thermometer at the Earth’s surface was −89.2 °C at Vostok station on July 21, 1983. The World Meteorological Organization maintains that value as the planet’s official record.

Satellites show the plateau can become even colder. A 2018 study led by NSIDC found about 100 spots with snow-surface temperatures near −98 °C in small depressions above 3,800 meters between Dome A and Dome F. Because this is the temperature of the snow surface, not the air, it does not count as an official record; the air above would be around −94 °C.

On an annual average, Vostok station is near −55 °C, and the South Pole near −49 °C. On the coast, the annual average is generally between −10 °C and −20 °C.

The heat record for the continent and nearby islands is 18.3 °C, measured at the Argentine Esperanza base on the tip of the Peninsula on February 6, 2020. Considering the entire region south of 60° S, the record is 19.8 °C at Signy Island in the South Orkneys on January 30, 1982.

These peaks happen with foehn wind: air rises over the Peninsula mountains, loses moisture and descends on the other side dry and warmer. In a few hours, temperature can climb several degrees.

In the interior, warmth is relative. The highest temperature ever measured at the South Pole was −12.3 °C on December 25, 2011.

Although it holds most of the planet’s fresh water, Antarctica is a desert. Very cold air holds little vapor, and it hardly rains or snows inland. On the plateau, a year’s snowfall is equivalent to less than 5 centimeters of rain; at the South Pole, about 6 to 8 centimeters.

Across the continent on average, snowfall is equivalent to roughly 15 centimeters of rain per year, according to the British Antarctic Survey. The coast receives more, and the Peninsula is the wettest part, with frequent snow and even rain in summer.

In the interior, snow often does not fall from clouds: it forms in the very clean air itself, as tiny crystals that glitter in the sun, the so‑called diamond dust.

On the plateau, air in contact with the ice cools, becomes denser and flows downhill along the ice sheet toward the coast. That is katabatic wind. In valleys and bays where it channels, it can reach hurricane speeds.

The windiest place at sea level is Cape Denison in Commonwealth Bay in East Antarctica. There the daily maximum wind average is 71 km/h, and gusts exceed 200 km/h. Douglas Mawson’s expedition, which wintered there in 1912–1913, called the place the home of the blizzard.

High on the plateau, away from slopes, the wind is much weaker. At Dome C, where Concordia station is located, the winter average is near 10 km/h.

The McMurdo Dry Valleys in Victoria Land near the Ross Sea form the largest ice-free area in Antarctica, about 4,800 km². Surrounding mountains block glaciers, and katabatic wind dries the little snow that falls.

A year’s snow amounts to about 5 centimeters of water. Annual air averages range between −15 °C and −30 °C at the valley floors, and in summer temperatures hover around 0 °C, enough to melt glacier ice into streams that run for a few weeks each year.

There are lakes frozen year-round, some very salty, and Blood Falls, where iron-rich water emerges from Taylor Glacier and turns red on contact with the air. Because they resemble Mars’ surface, the valleys are used to test space mission equipment.

The East Antarctic plateau has the most extreme climate: very dry air, clear skies much of the time, temperatures below −60 °C in winter and around −30 °C in summer. Air pressure is low, and the altitude feels higher to the body.

The coast is less cold and cloudier, with strong winds and snowstorms. The Peninsula, farther north and surrounded by sea, has the mildest climate: in summer temperatures usually range from 0 °C to a few degrees above, and in winter the monthly average is generally between −5 °C and −15 °C.

The Peninsula was also one of the regions that warmed most in the Southern Hemisphere in the second half of the 20th century: Faraday station, now Vernadsky, recorded about 3 °C higher annual average over 50 years. That warming and what it changes are discussed in Antarctica and Earth’s climate.

In Antarctica, the year is divided into a short summer and a long winter. Summer runs from December to February, with daylight all day across much of the continent. October, November and March are transition months.

Winter lasts from April to September. Inland, temperatures fall quickly in autumn and then remain nearly steady, without a clearly colder month, until the return of sunlight. Meteorologists call this a winter without a core.

Almost all field research and the arrival of people and supplies take place in summer. In winter, darkness, cold and sea ice isolate most stations for months. How the light changes through the year is covered in Light and sky in Antarctica; why the seasons exist is explained on the Seasons page in Earth and Tourism.