The Driest Place on Earth: Atacama vs. Antarctica

In South America, the Atacama Desert — also known as the Desierto de Atacama — is a hotspot of extreme aridity.

This arid region receives very little rainfall, with some weather stations in the area reporting only dry air for decades. The average rainfall in some areas is less than 0.04 inches (1 millimeter) annually.

Such a dry climate results from a combination of factors: cold ocean currents from the Pacific Ocean, the rain shadow effect from the Andes Mountains and nearby mountains that block moist air.

The Salar de Atacama, also known as the Atacama Salt Flat, lies in the heart of this desert and showcases an eerie beauty shaped by extremely low humidity and salty terrain.

You’ll find San Pedro de Atacama, a high-altitude desert town turned tourist hub, not far from the Salar de Atacama. Though dry, it’s rich in culture, science and even human remains that tell stories of ancient civilizations. Fossils and fossil evidence of life abound, preserved in this harsh environment by lack of moisture.

Earth's Martian Twin

The extreme dryness and barren terrain of the Atacama Desert have made it an ideal testing ground for Mars exploration missions. Scientists and engineers frequently use its otherworldly landscapes and harsh conditions to simulate the Red Planet’s environment, testing rovers, habitats and life-detection equipment.

Due to its remarkably low humidity and minimal organic activity, the Atacama closely mirrors Martian conditions, helping researchers refine techniques for future missions seeking signs of life.

It might be surrounded by ice, but Antarctica’s McMurdo Dry Valleys are the largest ice-free region on the continent.

That’s because katabatic winds — super-chilled air that reach speeds of over 200 mph (322 km/h) — descend from the mountains and evaporate all moisture. These dry valleys experience dry weather and almost no significant rainfall.

Though snow cover exists in the surrounding areas, this terrain sees little to no actual snow accumulation on the ground. The cold air and unique topography block seaward flowing ice, creating a kind of weather-proof vacuum.

Scientists study these valleys because they closely resemble the Martian environment. In fact, NASA has tested future Mars missions here, analyzing microbial life, photosynthetic bacteria and survival strategies in extreme conditions.

The Atacama might rival the Namib Desert in Africa or the Arabian Desert for heat and dryness, but its lack of rainfall is unmatched. Meanwhile, the Sahara Desert, while hotter and bigger, gets more rain than either the Atacama or the McMurdo Valleys.

Coastal cities near these deserts, like Pelican Point in Namibia or towns along the Pacific Coast, sit close to some of the most rain-starved places on Earth. In both the Atacama and McMurdo regions, coastal areas and desert floor environments feature unique adaptations in geology and life.

The Atacama also includes regions like the Pampa del Tamarugal, and it’s been vital to the mining industry for centuries. It’s dry, yes, but it’s also a resource-rich landscape bathed in high temperatures, high-altitude air and light pollution-free skies perfect for astronomy.

Understanding the driest place on Earth helps researchers better comprehend dry air, dry climate and how animal species adapt to desert extremes. Whether it’s the parched soils of Chile's Atacama Desert or the frozen silence of the McMurdo Valleys, these areas offer insight into life’s limits — and possibilities.

So the next time someone mentions deserts, remember: it’s not just sand and sun. Sometimes, it's salt flats and weather stations, strong winds, and ancient mysteries.