Rare Blanket of Snow Falls in Chile’s Atacama, the World’s Driest Desert
The extraordinary event temporarily shut down equipment at the ALMA Observatory, and the snow reached the telescope’s main operations facility for the first time in 12 years
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Last week, astronomers stationed at the Atacama Large Millimeter/submillimeter Array (ALMA) Observatory in northern Chile awoke to a rare sight: fresh snow had fallen in the world’s driest nonpolar desert.
The Atacama Desert, known for its arid and rocky landscapes that evoke the red surface of Mars, was covered instead with a shocking dusting of white.
Precipitation during any season is rare in the 40,000-square-mile Atacama, which sits within a double rain shadow created by unique regional geography. To the desert’s west, the Pacific Ocean’s cold Humboldt Current flows north along the Chilean coast, cooling the air above and limiting the formation of rain clouds. To its east, the tall Andes Mountains block the westward movement of most atmospheric moisture.
Need to know: What is the ALMA Observatory?
The Atacama Large Millimeter/submillimeter Array is a powerful radio observatory consisting of 66 antennas. Fifty are in its main array and act as a single telescope to study the formation of stars and molecular clouds in the early universe.
Across the Atacama, most moisture exists sparingly in camanchaca, a dense fog. In some parts of the desert, rain has never been recorded.
Some of the Atacama’s only reliable precipitation falls as snow on exceptionally high-elevation plateaus. In areas above 16,500 feet in elevation, such as where a cluster of ALMA antennas sits on the Chajnantor Plateau, anywhere between 8 and 31 inches of snow might fall over the course of a year. Snow usually occurs during the “Altiplanic winter,” a localized weather event that brings precipitation in February, and during the Southern Hemisphere’s winter in June and July.
AWESOME! The Atacama Desert in Chile, the driest in the world, is SNOWY! pic.twitter.com/ltfMmUWqha
— ALMA Observatory (@almaobs) June 26, 2025
“In winter, some storms are fueled by moisture from the Pacific, which can extend precipitation even to the Atacama Desert’s coastal areas,” Raúl Cordero, a climatologist at the University of Santiago in Chile, tells Live Science’s María de los Ángeles Orfila.
But snowfall at 9,500 feet, where ALMA’s main operations support facility is situated, is exceedingly uncommon. There, last week’s weather marked the first recorded snow in 12 years, according to local media.
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“AWESOME! The Atacama Desert in Chile, the driest in the world, is SNOWY!” the observatory wrote on X.
The event was so unprecedented in recent history that it suspended scientific operations at ALMA’s radio telescope array, reports Live Science. The observatory’s antennas entered “survival mode” as wind chills dropped to minus 18 degrees Fahrenheit. The equipment has been temporarily reoriented downwind for its protection.
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“Once the storm passes, snow-clearing teams are immediately activated to visually inspect each antenna before resuming observations,” ALMA representatives tell Live Science. “This has to happen fast, as some of the best observing conditions occur just after a snowfall: The cold helps lower air humidity, which is what most interferes with our measurements.”
While the unusual event hasn’t been directly linked to climate change, Cordero says to the Agence France-Presse that climate models do indicate “this type of event, meaning precipitation in the Atacama Desert, will likely become more frequent.”
