•NASA and the National Snow and Ice Data Center (NSIDC) say that Antarctic sea ice is likely to reach its annual maximum on September 14, 2026. At that time, the ice cover will have reached about 17.59 million square kilometers (6.79 million square miles), the third lowest maximum on record since satellite observations began, according to a NASA Earth Observatory report. Antarctic sea ice typically peaks in September, at the end of the Southern Hemisphere’s winter, and reaches its minimum in February. Unlike the Arctic, which is an ocean basin surrounded by land, Antarctica is a large landmass surrounded by ocean; this geographic arrangement provides more space for the ice to expand during the winter and melt more during the summer.
Current data show that total Antarctic sea ice has increased by about 1 percent per year from 1979 to 2014. But it is unclear whether this increase is a sign of a meaningful change; Antarctic ice cover varies greatly from year to year. In 2012-2014, three consecutive years of record-breaking maximum winter sea ice by satellites occurred during a period when Arctic ice sheets were in a steep decline.
To determine the ice area, scientists rely on satellites equipped with passive microwave sensors that measure the microwave energy naturally emitted by the Earth. Sea ice emits more of this energy than open water, so it stands out in microwave images. Microwaves pass through clouds, so satellites can observe sea ice regularly, regardless of weather conditions. The records began with data collected by NASA’s Nimbus-7 satellite in late 1978; then, from 1987, the Defense Meteorological Satellite Program (DMSP) satellites, and from 2002 to 2011, NASA’s Aqua satellite. In 2025, scientists began using observations from the Japan Aerospace Exploration Agency’s GCOM-W satellite.
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