Which continent is the driest overall, including its polar desert?

Antarctica is the driest continent overall because most of its interior is a polar desert.

Although Antarctica is covered by a vast ice sheet, the interior receives extremely little precipitation. Some areas near the Ross Sea, known as the McMurdo Dry Valleys, can go years without significant snowfall or rain. Cold air holds very little moisture, and the continent's high elevation and circulation patterns limit incoming precipitation.

Antarctica is also the coldest and windiest continent. Nearly all of its fresh water is stored as ice rather than flowing in liquid rivers or lakes. Coastal regions receive more snow than the interior, while the Antarctic Peninsula has a comparatively maritime climate.

The Sahara is the world's largest hot desert, but Antarctica is larger when polar deserts are included. “Driest” refers to precipitation, not the visible absence of water. In fact, Antarctica contains most of Earth's ice and about 60 percent of its fresh water, yet that water is frozen and inaccessible to ordinary ecosystems.