List of Driest Places in the World

The driest place on Earth is not a sun-scorched desert. It is a network of ice-free valleys in Antarctica called the McMurdo Dry Valleys, where a combination of katabatic winds and surrounding mountains creates conditions so arid that scientists estimate no measurable precipitation has reached the ground there in roughly two million years. NASA has used the valleys as a proxy for studying the surface of Mars. Remove Antarctica from the list, and the Atacama Desert of northern Chile takes the crown as the driest non-polar place on the planet. Some weather stations in the Atacama have never, in the entire history of their records, registered a single drop of rainfall. The desert sits in a rare double rain-shadow — blocked from Pacific moisture by a coastal range and from Amazonian moisture by the Andes — and its soil is chemically so close to Martian regolith that ESA and NASA use it for rover testing. Dryness is measured in millimetres of precipitation per year. For comparison, the global land average is about 715 mm, and a typical humid tropical rainforest receives over 2,000 mm. The entries on this list average between 0 and 25 mm — most of them less than a single rainy day in a temperate city. Several of the driest places on Earth are also remarkably cold. Antarctica, the Arctic coastline, and the high Andes all combine extreme cold with extreme aridity. It is a reminder that the word 'desert' is defined by precipitation, not temperature — a fact that continues to surprise people for whom 'desert' is inseparable from dunes and camels.