Abstract:
In August 2026, the famous Atacama Desert in northern Chile experienced an extremely rare weather event. Several consecutive winter storms swept through the area, covering a land known for extreme drought with widespread snowfall, turning the desert landscape that was originally brown and volcanic tones suddenly into white. Not only was the snowfall unusually widespread, it was also accompanied by heavy rainfall, strong winds and flooding, even forcing the local observatory to temporarily suspend operations.
The Atacama Desert is one of the driest non-polar regions on Earth, with some areas experiencing no measurable rainfall for many years. Therefore, widespread snow accumulation here is a very rare event in itself. Snowfall isn't something that never happens, though. Similar winter snowfall events occurred in the area in 2011 and 2025. The weather process in August 2026 was particularly eye-catching because one of the storms had a very large impact. The snow fell from the Andes Mountains all the way west across the desert and even approached the Pacific Coast.
Satellite records from NASA and the U.S. Geological Survey clearly captured this change. The land imagers mounted on the Landsat 8 and Landsat 9 satellites captured images on August 6 and August 14 respectively. The before and after comparison showed that the originally exposed desert and plateau surfaces were covered with large areas of snow in just a few days.
Satellite imagery particularly shows the Chajnantor Plateau in the eastern Atacama Desert. It is part of the Altiplano-Puna volcanic complex with a very high altitude. It is also home to the world-famous astronomical observation facility Atacama Large Millimeter/submillimeter Array, ALMA.
ALMA consists of 66 high-precision antennas and is one of the most powerful radio astronomy observation facilities in the world. Because astronomical observations are very sensitive to weather and atmospheric conditions, when heavy snowfall and strong winds swept across the Chajnantor plateau, ALMA had to suspend operations and transfer the antenna into a protective "survival mode" to avoid equipment damage in extreme weather.
However, the unusual weather did not end with the first storm. In late August, the second winter storm hit northern Chile again and brought a new round of snowfall to a wider area, further escalating this year's already unusually wet winter.
The reason why the Atacama Desert is so dry is closely related to its special geographical location. It is located between the Andes Mountains and the Pacific Ocean. The towering Andes Mountains on the east side block a large amount of water vapor from the interior of South America. When moist air moves from east to west, most of the moisture is released in the form of precipitation before crossing the mountains. The air after crossing the mountains therefore becomes extremely dry, forming an obvious "rain shadow effect."
At the same time, there is also the cold Peru-Chile Current on the Pacific side. This cold snap will lower the temperature of the offshore air and inhibit much evaporation and cloud formation, further reducing the amount of water vapor that can actually be converted into rainfall.
Two factors work together to make the Atacama one of the most extreme arid environments on Earth. In the desert's driest core, annual rainfall can be as low as a dozen millimeters, with some locations recording even lower rainfall. Therefore, the visual contrast is particularly strong when large amounts of snow cover the desert.
However, this desert is not completely immune to unusual weather systems. Occasionally, cold-core cyclones that can move to lower latitudes, known as cutoff low-pressure systems, break through the stable atmospheric structure that normally maintains the Atacama's arid climate, bringing unusually cold and moist air into the area.
When temperatures are cold enough, this water vapor falls as snow; at lower altitudes, it can appear as unusually heavy rainfall. The storm that occurred in August 2026 is one of the manifestations of this rare weather process.
It is worth noting that the unusually wet winter in central and northern Chile in 2026 is not an isolated event. Before August, the local area had already experienced a severe weather process in July, which had a significant impact on the Norte Chico region of Chile. The subsequent August storms further intensified the abnormally wet conditions throughout the winter.
Climate scientists believe that the strengthening El Niño phenomenon may be one of the important background factors for this year's abnormal weather. Normally, the subtropical Pacific high pressure helps maintain dry weather along the northern and central coasts of Chile, but under the influence of El Niño, this high pressure system weakens.
At the same time, blocking high pressure is more likely to form in the South Pacific near the southern tip of South America. The superposition of these two atmospheric changes will push the storm track in the southern hemisphere toward the equator, making it easier for strong weather systems that are originally difficult to reach northern Chile to advance northward.
For the Atacama Desert, this means that the arid environment, which was originally firmly maintained by stable atmospheric circulation and geographical conditions, may be temporarily broken under certain weather conditions. Severe storms can carry unusually large amounts of water vapor into the desert, converting it into snow at higher elevations and heavy rainfall at lower elevations.
And the impact of this extreme weather is not just turning the desert white. For a region with chronic water shortages and extremely dry surface conditions, a large amount of precipitation in a short period of time can quickly trigger floods and mudslides. Abnormal weather in August 2026 has caused disasters such as floods and mudslides, and also affected local infrastructure and transportation.
From a satellite perspective, this event is particularly representative. The footage taken on August 6 showed that the Atacama Plateau still mainly showed its typical desert color; by August 14, large areas had been covered with snow, and the white surface extended westward from the Andes Mountains, forming a scene that was completely different from the usual appearance of this desert.
The "whitening" of the Atacama Desert once again demonstrates that even the most stable and extreme arid environment on earth is not completely immune to changes in global and regional atmospheric circulation. The local dryness is maintained by complex geographical and climatic conditions, but when large-scale climate phenomena such as El Niño change atmospheric circulation, rare heavy snowfalls and heavy rains may still break through these long-standing climate barriers.
For scientists, such rare weather events not only provide the opportunity to study climate change in the Atacama, but also help to further understand the relationship between El Niño, storm tracks, and atmospheric circulation in South America. For this desert, which is known as one of the most Martian environments on Earth, the "white storm" left in August 2026 will undoubtedly become a particularly eye-catching event in its extreme climate history.
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