Arctic sea ice extent for March set a record low in the 47-year satellite data record. Extent was below average everywhere except the East Greenland Sea. Nearly all March monthly average extents since 2004 have been well below the 1981 to 2010 average.
Overview of conditions
March Arctic sea ice extent averaged 14.14 million square kilometers (5.46 million square miles) (Figure 1a), the lowest in the 47-year satellite record and 150,000 square kilometers (58,000 square miles) below the previous record low March set in 2017. After a stall in ice growth at the end of February that persisted into early March, ice extent increased at a near-average pace until reaching a record low annual maximum extent of 14.33 million square kilometers (5.53 million square miles), on March 22 (Figure 1b). During this ice growth period, the ice edge expanded southwards in the Bering Sea, the Sea of Okhotsk, the Barents Sea, and the northern part of the East Greenland Sea. The ice edge also expanded along the southern edge of the Labrador Sea, while retreating slightly northwards in Davis Strait and the southern part of the East Greenland Sea.
After reaching its maximum extent on March 22, ice retreated most prominently in the Sea of Okhotsk and the Barents Sea. Extent also fell slightly in the East Greenland Sea and Davis Strait. The rate of ice loss from the March 22 through April 1 was 29,500 square kilometers (11,400 square miles) per day.
Figure 1a. Arctic sea ice extent for March 2025 was 14.14 million square kilometers (5.46 million square miles). The magenta line shows the 1981 to 2010 average extent for that month. Sea Ice Index data. About the data — Credit: National Snow and Ice Data Center
Figure 1b. The graph above shows Arctic sea ice extent as of April 2, 2025, along with daily ice extent data for four previous years and the record low year. 2024 to 2025 is shown in blue, 2023 to 2024 in green, 2022 to 2023 in orange, 2021 to 2022 in brown, 2020 to 2021 in magenta, and 2011 to 2012 in dashed brown. The 1981 to 2010 median is in dark gray. The gray areas around the median line show the interquartile and interdecile ranges of the data. Sea Ice Index data. — Credit: National Snow and Ice Data Center
Conditions in context
Temperatures at the 925 millibar level (approximately 2,500 feet above the surface) were above the 1981 to 2010 average around much of the Arctic region, with the exception of below-average temperatures over Hudson Bay (Figure 2a). The particularly high temperatures north of Greenland and the Canadian Archipelago are suspicious, notably because of their persistence over the past six months. The issue has been reported to NCEP. The sea level pressure in March characterized a typical Beaufort High north of Alaska, while low pressure settled over the Barents and Kara Seas, as well as the Bering Sea (Figure 2b).
Figure 2a. This plot shows the departure from average air temperature in the Arctic at the 925 hPa level, in degrees Celsius, for March 2025 relative to the 1981 to 2010 average. Yellows and reds indicate above average temperatures; blues and purples indicate below average temperatures. — Credit: NSIDC courtesy NOAA Earth System Research Laboratory Physical Sciences Laboratory
Figure 2b. This plot shows average sea level pressure in the Arctic in millibars for March 2025. Yellows and reds indicate higher air pressure; blues and purples indicate lower pressure. — Credit: NSIDC courtesy NOAA Earth System Research Laboratory Physical Sciences Laboratory
March 2025 compared to previous years
The downward linear trend in ice extent through 2025 for March is 38,000 square kilometers (15,000 square miles) per year or 2.5 percent per decade relative to the 1981 to 2010 average (Figure 3). Based on the linear trend, since 1979, March has lost 1.71 million square kilometers (660,000 square miles). This is equivalent to the size of Alaska.
Winter in review
Low sea ice extent persisted through most of the 2024 to 2025 winter season across much of the Arctic Ocean and seasonal ice zones. Early in the season, the lack of sea ice in southeastern Hudson Bay was the primary driver for a new record low Arctic sea ice extent in December. Ice formation in this region was delayed because a marine heatwave elevated sea surface temperatures that persisted through autumn. This heatwave followed an unusually early breakup of ice in the eastern and southern Hudson Bay last May, causing the ocean to take up a significant amount of solar energy. In the Barents Sea, the ice edge remained farther north than usual throughout winter. By February, all other Arctic regions experienced below-average sea ice, with the ice growth season concluding on March 22. The East Greenland Sea was the only exception, maintaining near-average ice extent for most of the winter.
Since reaching its maximum extent, sea ice rapidly retreated in the Sea of Okhotsk and the Barents Sea, with open water forming north of Franz Josef Land (Figure 4a). Ice concentrations also decreased in several areas, including within Hudson Bay where areas of open water had formed following the passing of an extratropical cyclone. (Figure 4b). The cyclone tracked along the southern edge of the bay, bringing strong winds from the south and east that triggered the ice break up in the region.
Sea ice thickness for the end of March exceeded 3 meters (10 feet) north of Greenland and in the northern part of the East Greenland Sea based on the Alfred Wegener Institute (AWI) CryoSat-2/Soil Moisture Ocean Salinity (CS2SMOS data product) (Figure 4c). Some locally thick ice was also present south of the New Siberian Islands. Ice thicknesses in the Chukchi Sea appear to have been between 2 and 3 meters (7 to 10 feet) thick, and was generally less than 2 meters (7 feet) thick in the Beaufort, Laptev, and Kara and Barents Seas. March sea ice in the Barents Sea is less than 1 meter (3 feet) thick.
Figure 4a. This NASA Advanced Microwave Scanning Radiometer 2 (AMSR2) image, taken on March 28, 2025, shows sea ice retreat in the Sea of Okhotsk and the Barents Sea and open water forming north of Franz Josef Land. — Credit: NASA
Figure 4b. This NASA Moderate Resolution Imaging Spectroradiometer (MODIS) image from March 27, 2025, shows reduced ice concentrations in southeastern Hudson Bay. — Credit: NASA Worldview application, part of the NASA Earth Science Data and Information System
Winters becoming less extreme for Arctic sea ice
The downward trend in sea ice extent during winter months is a clear sign of warming conditions. The amount of sea ice growth leading up to the winter maximum is as important as how sea ice persists through winter. Early in the satellite record, extent often exceeded 14 million square kilometers (5.41 million square miles) for over four months each winter. However, the duration above that level has declined substantially to two to three months over the last two decades. This past winter, 2024 to 2025, extent rose above 14 million square kilometers (5.41 million square miles) for only 21 days, less than half the number of the previous low set in 2018. And extent at a higher level of 15 million square kilometers (5.79 million square miles), which commonly lasted for over three months every winter, has over the past decade, become a rare and short-lived occurrence, with only five days total since the 2012 to 2013 winter.
Looking south
Following the Antarctic sea ice minimum extent on March 1, which tied for second-lowest with 2022 and 2024 and came just after the record low set in 2023, sea ice grew at a near-average pace (Figure 6a). Sea ice expanded rapidly in the last areas to lose ice—the Ross and western Amundsen Seas, eastern Weddell Sea, the Davis Sea off the ice front of the Amery Ice Shelf, and Pine Island Bay region. The Ross Sea area, in particular, had low sea ice concentration and ice extent slowly retreated in February, leading up to the minimum. Therefore, the upper ocean layer did not have time to accumulate solar energy. Freeze up has been slow in the Bellingshausen Sea, which is still largely ice free. Across Antarctica, and in the ocean area immediately surrounding the continent, March temperatures were generally above average until the last week of the month when overall cooler conditions prevailed.
Figure 6a. The graph above shows Antarctic sea ice extent as of April 2, 2025, along with daily ice extent data for four previous years and the record maximum year. 2025 is shown in blue, 2024 in green, 2023 in orange, 2022 in brown, 2021 in magenta, and 2014 in dashed brown. The 1981 to 2010 median is in dark gray. The gray areas around the median line show the interquartile and interdecile ranges of the data. Sea Ice Index data. — Credit: National Snow and Ice Data Center
Figure 6b. This map compares Antarctic sea ice extent at the beginning and end of March 2025. Sea ice extent on March 1 is depicted as white, while sea ice extent on March 31 is depicted as dark blue. Ice extent on both dates is depicted as light blue. Missing data appears in yellow. — Credit: National Snow and Ice Data Center
References
Soriot, C., J. Stroeve, and A. Crawford. 2025. Record early sea ice loss in southeastern Hudson Bay in spring 2024. Geophysical Research Letters, 52, e2024GL112584. doi:10.1029/2024GL112584