What is the driest desert in the world?
Quick answer
The Atacama Desert in northern Chile is the driest nonpolar desert on Earth. Some weather stations there have never recorded rain, and parts receive only about 1–3 mm a year. Only Antarctica’s McMurdo Dry Valleys, a polar desert, are drier. The Atacama is so Mars-like that NASA tests rovers there.
Key facts
- Location
- Northern Chile, between the Andes and the Pacific
- Area
- About 105,000 km²
- Rainfall
- As little as 1–3 mm a year in the driest parts
- Age
- Possibly the oldest continuously dry desert, millions of years
Why it’s so dry
The Atacama is trapped between two rain blockers:
| Barrier | Effect |
|---|---|
| The Andes to the east | Block moist air from the Amazon, creating a rain shadow |
| The cold Humboldt Current offshore | Cools the air, so it can’t form rain clouds |
| A high-pressure zone | Keeps air sinking and dry |
Life in the driest place
Near the coast, fog called camanchaca rolls in from the Pacific. Some villages use giant mesh fog catchers to collect drinking water. Lichens, cacti and some microbes survive on this moisture.
The flowering desert
Every few years, often during El Niño events, unusual rain makes the southern Atacama burst into color with wildflowers, an event called the desierto florido (flowering desert).
A window to the universe
The Atacama’s dry air, high altitude and clear skies make it one of the best places on Earth for astronomy. It hosts:
- ALMA, a giant radio telescope array at about 5,000 m altitude
- The Very Large Telescope at Paranal
- The Vera C. Rubin Observatory, which began surveying the sky in 2025
Practice for Mars
NASA and other agencies test rovers and life-detection instruments in the Atacama because its soil is so similar to Mars. See the first rover to operate on Mars.
Deserts by type
| Record | Desert |
|---|---|
| Driest overall | McMurdo Dry Valleys, Antarctica |
| Driest nonpolar | Atacama |
| Largest overall | Antarctica |
| Largest hot desert | Sahara |
For deserts closer to home, see the largest desert in North America and where the Gobi Desert is.
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