NASA and NSIDC say the ice peaked on September 14, about a million square kilometers short of average, making the past four winters the four lowest on record.
Antarctic sea ice hit its 2026 winter peak on or around September 14, covering about 17.59 million square kilometers, NASA and the National Snow and Ice Data Center say. That is the third-lowest maximum since satellite records began in 1979.
The ice fell about a million square kilometers short of average, roughly twice the size of Spain. The four lowest winter peaks on record have now all come in the past four years.
Scientists say the ice has been shrinking faster than usual since the peak. The next marker is the summer minimum, usually in February, which could bring another very low reading.
Antarctica’s frozen ocean came up about a million square kilometers short this winter, an area roughly twice the size of Spain. NASA and the National Snow and Ice Data Center (NSIDC) say Antarctic sea ice reached its 2026 maximum on or around September 14, covering an estimated 17.59 million square kilometers, or 6.79 million square miles.
That makes it the third-lowest winter peak in the satellite record, and it completes a run scientists find hard to dismiss: the four lowest maximums ever measured have now all happened in the last four years. Sea ice sits at the bottom of the world, but it shapes how much heat the ocean soaks up, how stable Antarctica’s giant ice shelves stay and whether penguins and krill have somewhere to live.
The 2026 Antarctic sea ice maximum came on September 14, and by NASA’s count it ranks third-lowest since records began in 1979. NSIDC held off declaring the peak for a while because ice levels can swing a lot at that point in the season. After the ice kept shrinking from mid-September, Walt Meier, a senior scientist at the center, said the maximum had been reached.
Antarctic sea ice goes through one of the biggest seasonal swings on Earth. It melts back to below 2 million square kilometers in recent Februaries, then grows to more than 17 million by September, at the end of the Southern Hemisphere winter.
The geography explains why. The Arctic is an ocean hemmed in by land, while Antarctica is a continent ringed by open ocean. Ice around Antarctica has room to spread far out in winter, but that also pushes it into warmer waters where it melts quickly in summer.
This is a sharp turnaround. Between 1979 and 2014, Antarctic sea ice actually grew by about 1 percent per decade, and satellites logged new record winter highs three years running, from 2012 to 2014, even as Arctic ice was shrinking fast.
The growth stopped in 2015, and big declines began in 2016. There have been small rebounds since, but coverage has mostly stayed below normal. Both the lowest summer minimum and the lowest winter maximum on record came in 2023.
Scientists have been careful about calling this a permanent shift, because Antarctic ice varies so much from year to year. Some are now more direct. Ariaan Purich, a Southern Ocean expert at Monash University in Melbourne, said four record-low winters in a row point to a system that has changed, and added that it is “a now problem” rather than a future one.
Part of the answer is weather. In June, the Antarctic Peninsula had a heat wave with temperatures 20C above normal, and scientists spotted a France-sized patch of open water where ice should have been. In early August, when the ice should have been growing steadily, a large stretch of the Amundsen Sea south of the Pacific lost ice instead.
Researchers point to the El Niño pattern in the tropical Pacific, which shifts winds and can park storm systems over the ice and break it up. Phil Reid, who monitors Antarctic conditions at Australia’s Bureau of Meteorology, said he thinks the ice would be in a similar place even without El Niño. His point was simple: if the water is too warm, there will be less ice.
The decline has continued since the peak. Will Hobbs, an Antarctic sea ice expert at the University of Tasmania, said the ice has been dropping faster than usual and warned of another low summer ahead.
Melting sea ice doesn’t raise sea levels directly, because it is already floating, like an ice cube in a glass. The danger is what it protects. Sea ice shields Antarctica’s ice shelves from rough ocean waves and warm water. Those shelves act like doorstops for glaciers and the continent’s ice sheet, which could raise global sea levels by many meters if it slid into the ocean. Coastal cities from Miami to London have a stake in that.
Sea ice also works like a giant mirror. Bright ice bounces sunlight back to space, while dark open water absorbs it. Less ice means the Southern Ocean takes in more heat, which can feed further warming.
Wildlife feels it first. Algae grow on the underside of sea ice and feed krill, a base of the Antarctic food chain. Emperor penguins need stable ice to breed and raise their chicks, and scientists worry about what repeated low years will do to them.
NASA tracks Antarctic sea ice with satellites carrying passive microwave sensors, which pick up the faint microwave energy Earth gives off naturally. Ice gives off more of it than open water, so it stands out clearly. Microwaves also pass straight through clouds, which matters in one of the stormiest places on the planet.
Scientists count an area as ice-covered when at least 15 percent of it is ice, then add up those areas to get the sea ice extent. The record began in late 1978 with NASA’s Nimbus-7 satellite. Military weather satellites joined in 1987, NASA’s Aqua satellite contributed from 2002 to 2011, and since 2025 the record has also used Japan’s GCOM-W satellite.
Next up is the summer low, usually reached in February. After this winter’s weak peak and a faster-than-usual retreat, scientists will be watching closely to see whether the coming summer sets another record.
NASA and NSIDC say it peaked on or around September 14, 2026, at about 17.59 million square kilometers (6.79 million square miles), the third-lowest on record.
Not this winter. The record low maximum and minimum both came in 2023. But the four lowest winter peaks have all occurred in the last four years.
Not directly, since it already floats. But losing it exposes ice shelves to the ocean, which can speed up land ice that does raise sea levels.
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