Antarctic sea ice likely reached its widest extent of 2026 on 14 September, covering an estimated 17.59 million square kilometres. NASA Earth Observatory ranks that winter maximum as the third-lowest in the satellite record, which began in late 1978.
This ice forms from seawater around Antarctica. It expands through the Southern Hemisphere winter and retreats in summer. A low winter maximum means it did not spread as far as in most measured years. It does not measure the ice on the Antarctic continent.
What does “extent” measure?
Sea-ice extent counts ocean areas where satellite measurements show at least 15 percent ice cover. It describes how far the floating ice reaches, not its thickness or total volume. It should not be confused with changes in Antarctica’s land-based ice sheet.
NASA notes that Antarctic winter sea ice reached record highs from 2012 to 2014, before marked declines began in 2016. The record-low maximum occurred in 2023. Coverage also varies substantially from year to year, so scientists are still assessing whether the recent lower levels represent a lasting shift.
In its 7 October analysis, the National Snow and Ice Data Center (NSIDC) said Antarctic sea ice had retreated sharply after its September peak. By 6 October, its extent was close to the record low for that calendar date. Continued measurements will show how the warmer season develops; the winter maximum alone cannot establish the cause of this year’s conditions.
Antarctic sea ice on 14 September 2026. The yellow outline shows the 1981–2010 median ice edge. Image: NASA Earth Observatory/Michala Garrison, using NSIDC data.
