Two consecutive winter storms in August 2026 covered parts of the Atacama Desert in northern Chile with a rare blanket of snow, extending from the Andes mountains to near the Pacific coast.
Satellite imagery from NASA captured the severe weather event, which forced major astronomical observatories, including the high-altitude Atacama Large Millimeter/submillimeter Array, to suspend operations and place equipment in weather protection modes.
The Atacama Desert is widely recognized as one of the driest places on Earth, with hyper-arid plateau areas receiving minimal rainfall annually. Because of its high altitude, thin air, and low humidity, the region hosts several of the world's most advanced astronomical facilities.
NASA satellite observations recorded conditions on August 6 and August 14, 2026, tracking changes before and after the first wave of severe winter weather. The images showed detailed views of the Chajnantor plateau within the Altiplano-Puna volcanic complex, where the ALMA radio telescope is located.
As snow and powerful winds moved across the plateau, operators at ALMA suspended scientific activities and positioned the facility's antennas into protective stow positions. Elsewhere in Chile, severe winter conditions caused widespread disruption, including a blizzard that left 39 miners isolated at a remote mining camp, storm damage that killed at least four people and left hundreds homeless, and weather conditions that forced the closure of 90 percent of the country's ski slopes.
Widespread satellite views of desert snow
A second winter storm during the latter half of August covered an even larger swath of northern Chile with fresh snow. Satellite images taken by NASA on August 19, 2026, showed the snowpack stretching westward from the high Andes, across the hyper-arid interior of the desert, and reaching close to the Pacific coastline.
The snowfall reached areas just south of the Chilean port city of Antofagasta. This coastal region is home to several other prominent astronomical observatories, a number of which were also forced to halt operations during the winter storm.
Weather experts attribute the unusual precipitation to specific high-altitude atmospheric disturbances known as cut-off lows. These systems develop when low-pressure cells break away from the main jet stream and drift over northern Chile.
René Garreaud, an atmospheric scientist at the University of Chile, said that a similar cut-off low system caused snowfall in the Atacama Desert in 2025, following a previous snowfall event in 2011. However, Garreaud noted that the late August 2026 storm originated from an exceptionally large low-pressure area that spanned a vast section of the Southern Hemisphere, reaching from the southern tip of South America into the subtropics.
Garreaud explained that the large atmospheric disturbance combined with abundant moisture from the Pacific Ocean to generate precipitation across an unusually wide zone. Rainfall and snow fell offshore, along the coast, across the core of the desert, and over the Andes range. He added that total precipitation reached levels rarely observed in the hyper-arid region.
Coastal rainfall and disaster response
While higher elevations received heavy snow, lower coastal areas experienced intense rain. In the northern coastal town of Taltal, weather monitoring recorded nearly 40 millimeters of rainfall over a three-day period, an amount roughly 10 times the area's average annual precipitation.
The downpours triggered severe flash floods and mudslides across parts of northern Chile. Officials at the National Disaster Prevention and Response Service, known as SENAPRED, reported that thousands of residents were affected by the storms, with hundreds of homes sustaining extensive damage.
Atmospheric scientists identified a strengthening El Niño climate pattern as the primary background driver for the abnormally wet winter in north-central Chile. The August storms followed another major weather system in July 2026 that caused significant disruption in the Norte Chico region.
Garreaud explained that during an El Niño event, the Pacific subtropical high-pressure system, which normally keeps northern Chile dry, weakens significantly. At the same time, a blocking high-pressure system tends to form in the South Pacific near the tip of South America. Together, these atmospheric shifts redirect Southern Hemisphere storm tracks further north toward the equator, bringing rare moisture and winter storms to the Atacama region.
