Antarctic sea ice likely reached its annual maximum on September 14, 2026, at an estimated 17.59 million square kilometers (6.79 million square miles). The extent ranks as the third-lowest maximum in the satellite record, based on data from NASA and the National Snow and Ice Data Center (NSIDC).
The 2026 number sits at one end of a pattern that shifted in 2015. From 1979 until 2014, Antarctic sea ice expanded by about 1 percent per decade. Whether that growth was meaningful is uncertain, since the extent around Antarctica varies considerably from year to year. Satellites logged new record highs for winter sea ice in each of three straight years, 2012 through 2014. Those highs came while Arctic ice was declining steeply.
The climb ended in 2015. Significant decreases around Antarctica began in 2016. Some years since have brought small rebounds, but overall coverage has remained largely lower than normal. Both the record low minimum and the record low maximum occurred in 2023. Scientists are watching each year to determine whether the decline is long-term change or a statistical fluctuation.
Antarctic Geography Explains the Ice Cycle
The Arctic is an ocean basin surrounded by land. The Antarctic is a large continent surrounded by ocean. Sea ice around the continent has more room to expand during winter because of that geography. The ice also extends into warmer latitudes, which drives more melting in summer.
Antarctic sea ice usually peaks in September, near the end of the Southern Hemisphere winter. It retreats to a minimum in February. The 2026 maximum arrived on September 14, in line with that seasonal pattern. The report updates an earlier World of Change feature on Antarctic sea ice, a series tracking long-term change on Earth's surface through satellite imagery.
Microwave Sensors See Ice Through Clouds
Sea ice extent comes from passive microwave sensors on satellites. The sensors measure microwave energy that Earth naturally emits. Sea ice emits more of that energy than open water, so it stands out in the imagery. Because microwaves pass through clouds, the satellites can observe ice regularly regardless of weather.
The record began in late 1978 with NASA's Nimbus-7 satellite. Defense Meteorological Satellite Program (DMSP) satellites joined in 1987. NASA's Aqua collected data from 2002 to 2011. Scientists added observations from the Japan Aerospace Exploration Agency's GCOM-W satellite in 2025.
Scientists count an area as ice-covered when ice concentration reaches at least 15 percent, the threshold used in satellite data. The published maps show average sea ice concentration for September and the following February, season by season from 1990 to 2026. Opaque white marks the highest concentrations, and dark blue marks open water.
The February Minimum Matters for Voyage Planning
The seasonal ice cycle is relevant to choosing when to sail. The 2026 maximum came in September. The ice then retreats through the season to its minimum in February. A voyage in February runs at the smallest sea ice extent of the year.
Scientists will keep observing each year to determine whether the post-2016 decline is a lasting change or a fluctuation. That answer will shape future seasons. For the current one, the pattern is clear: the maximum was the third-lowest on record, and the ice continues its retreat toward the February minimum.
The question worth putting to an operator is how the current ice season affects the specific route and landing sites under consideration. Regional ice conditions vary from year to year, and the continental average does not settle what a ship will find along its planned route.