Antarctica is the driest continent on Earth. Despite holding about 70% of the world’s fresh water locked in its ice sheet, the continent receives an average of only 150 millimeters (about 6 inches) of precipitation per year in liquid-water equivalent. That puts it well below the 250-millimeter threshold that defines a desert, making Antarctica, by definition, the world’s largest one.
Why Antarctica Qualifies as a Desert
A desert is any region receiving less than 250 millimeters (10 inches) of precipitation annually. Most people picture sand dunes and scorching heat, but the classification is strictly about moisture. The Sahara, the Gobi, and Antarctica all meet this criterion. Antarctica’s continent-wide average of roughly 150 millimeters places it firmly in desert territory, and vast stretches of the interior are far drier than even the Sahara’s driest zones.
The elevated interior plateau receives less than 50 millimeters of precipitation per year. The South Pole gets about the same annual moisture as parts of the deep Sahara. Coastal regions are wetter, generally exceeding 200 millimeters, with some areas near the Bellingshausen Sea topping 1,000 millimeters. But those wet fringes don’t change the overall picture: most of the continent is profoundly arid.
Why Cold Air Means Dry Air
The fundamental reason Antarctica is so dry comes down to temperature. Air’s ability to hold water vapor depends directly on how warm it is. As temperature drops, fewer water molecules have enough energy to remain as vapor, so the saturation point plummets. At the extreme cold of the Antarctic interior, where winter temperatures can fall below minus 60°C (minus 76°F), the atmosphere simply cannot carry meaningful moisture. Even when weather systems attempt to deliver precipitation, there is almost no water vapor available to fall.
This is the same principle behind the dry air you feel on a cold winter day in temperate climates, just taken to an extreme. Antarctica’s interior plateau sits at high elevation (roughly 2,500 to 4,000 meters above sea level), which compounds the effect. The air is not only bitterly cold but also thin, further reducing its moisture capacity.
Katabatic Winds Strip Moisture Away
Antarctica’s dryness isn’t only about low precipitation. Powerful gravity-driven winds called katabatic winds constantly drain cold, dense air from the high interior down toward the coast. These winds can sustain speeds above 150 kilometers per hour and they carry extremely dry air from the plateau. As this dry air flows outward, it causes snow and ice to sublimate, converting solid ice directly into vapor that gets swept away without ever becoming liquid water.
Research using weather models and isotope tracking suggests that sublimation driven by katabatic winds reduces snowfall by about 17% across the continent as a whole. Along the East Antarctic coast, where these winds are especially fierce, the reduction can reach 35%. So even the snow that does fall often doesn’t stay on the surface. The wind essentially vacuums moisture away, reinforcing the continent’s desert conditions.
The McMurdo Dry Valleys
The most extreme example of Antarctic dryness is the McMurdo Dry Valleys, a roughly 4,800-square-kilometer expanse of bare rock and gravel in East Antarctica. These valleys have been largely ice-free for millions of years. Surrounding mountains block the flow of glaciers into the valleys, and the katabatic winds that pour through them are so effective at sublimating any snow that the ground remains exposed.
Annual precipitation in parts of the Dry Valleys may be as low as 10 to 20 millimeters. The relative humidity can drop to extremely low levels, making these valleys among the closest analogs to the surface of Mars that exist on Earth. NASA has used them as testing grounds for planetary exploration instruments for exactly this reason. If you stood in the Dry Valleys, you would see no ice, no snow, and no visible water in any direction, just wind-scoured rock and desiccated soil.
How Dryness Varies Across the Continent
Antarctica’s precipitation follows a steep gradient from coast to interior. Atmospheric rivers, the narrow bands of moisture-laden air that deliver much of the continent’s precipitation, deposit around 100 millimeters per year along the coast but only about 10 millimeters by the time they reach the deep interior. This tenfold drop happens over a relatively short distance as air rises over the ice sheet and loses nearly all its remaining moisture.
The Antarctic Peninsula, which juts northward toward South America, is the wettest part of the continent. It experiences the most surface melting days during summer, and its ice shelves see the highest melt rates. In contrast, the East Antarctic Plateau is one of the driest places on the planet by any measure, rivaling the driest hot deserts for sheer lack of moisture.
What Dryness Does to People in Antarctica
The extreme aridity has real consequences for the researchers and support staff who live on Antarctic bases. Skin dehydration is one of the first effects. Observational studies of base camp researchers show an initial drop in skin hydration and oiliness upon arrival, along with rougher skin texture. The body does adapt: by about day 45, hydration and skin condition typically improve as the skin’s barrier adjusts. But the early weeks can be uncomfortable, with cracking and dryness common on exposed areas.
The dry air also creates indirect skin risks. Limited water supplies and harsh conditions restrict bathing, which can lead to overgrowth of certain skin fungi and higher rates of seborrheic dermatitis and dandruff. Frostbite is the dominant skin injury, accounting for 95% of cold-related cases, with the face being the most commonly affected area. The combination of dry air, extreme cold, and intense UV reflection off ice and snow makes Antarctica one of the harshest environments for human skin anywhere on Earth.
Is Antarctica Getting Wetter?
There are signs that precipitation patterns are shifting. The period from March 2024 to February 2025 saw unusually heavy snowfall, with net snow accumulation running about 200 billion tons above the annual average of roughly 2,400 billion tons. This excess fell primarily along the Dronning Maud Land coast, central East Antarctica, and the Getz Ice Shelf area of West Antarctica. The extra snow was significant enough to partially offset ice sheet losses and reduce the continent’s contribution to sea level rise for that period.
A warmer atmosphere can hold more moisture, and rising global temperatures are expected to increase the amount of water vapor reaching Antarctica over time. Atmospheric rivers are projected to play a growing role in delivering precipitation to the continent. But even with these increases, Antarctica will remain a desert by any standard definition. The interior is so cold and so far from moisture sources that meaningful change to its fundamental aridity would require a transformation in global climate far beyond current projections.