Arctic sea ice shrank to its smallest extent of the year on Sept. 12, covering about 1.78 million square miles (4.60 million square kilometers), NASA announced with the National Snow and Ice Data Center (NSIDC) at the University of Colorado Boulder. That ties 2008, 2010 and 2025 for the 10th-lowest summer minimum since continuous satellite measurements began in late 1978.

At the other end of the planet, NSIDC's preliminary analysis indicates Antarctic sea ice most likely reached its winter maximum on Sept. 14 at 6.79 million square miles (17.59 million square kilometers). If that date holds, it would be the third-lowest Antarctic maximum in the satellite record.

Both results are preliminary. NSIDC cautions that shifting winds or late-season melt could still push the Arctic figure lower, as happened in 2005 and 2010, and that Antarctic extent often fluctuates near its peak. The center plans a full analysis in early October.

A Low Minimum on a Long Plateau

The 2026 minimum continues a pattern that has held for two decades. The 20 lowest Arctic minimums in the satellite record all occurred from 2007 through 2026, according to NASA.

The decline has also slowed. "We've plateaued, but we're still low relative to the earlier part of the record," said Walt Meier, a senior research scientist at NSIDC.

According to NSIDC's analysis of the minimum, September minimum extent has shown no significant decline over the past two decades, and scientists are still debating why. Over the full record from 1979, however, the minimum has fallen about 11.8% per decade relative to the 1981 to 2010 average, a loss of roughly 28,300 square miles (73,200 square kilometers) of ice per year.

This year's minimum sits about 467,000 square miles (1.21 million square kilometers) above the record low set on Sept. 17, 2012. It is also about 625,000 square miles (1.62 million square kilometers) below the 1981 to 2010 average minimum, a gap NSIDC compares to the size of Alaska. The minimum arrived two days earlier than the 1981 to 2010 median date of Sept. 14.

Weather helps explain the plateau. Over the last decade, increased cloud cover has kept sunlight from further speeding summer melt, according to Linette Boisvert, a sea ice scientist at NASA's Goddard Space Flight Center in Greenbelt, Maryland.

Alaska climate specialist Rick Thoman, writing in his Alaska and Arctic climate newsletter, pointed to another likely factor. Ice in the lower-latitude Arctic now largely melts out by early September, he wrote, leaving the remaining ice mostly north of 76 degrees north, where strong solar heating lasts a shorter time. He added that this year's minimum is still nearly 15% lower than in any year before 2007, and that the typical minimum today is 34% smaller than the early 1980s average.

Why Rankings Differ by Dataset

Sea ice rankings shift slightly depending on the dataset and how close values are grouped. NSIDC treats values within about 15,000 square miles (40,000 square kilometers) of each other as ties, which places 2026 in a four-way tie for 10th. Thoman's reading of the same Sea Ice Index data ranks 2026 tied with 2025 for 11th.

An independent dataset gives a similar picture. In its latest sea ice briefing, the U.K. Met Office reported that the European OSI SAF index put the Arctic minimum on Sept. 12 at 14th-lowest, and showed Antarctic sea ice reaching 18.12 million square kilometers on Sept. 11, which would also be third-lowest if not exceeded. The absolute numbers differ because each index is built with its own methods, but both point to a low Arctic minimum and a near-record-low Antarctic peak.

What the Minimum Looked Like Off Alaska

Regional patterns matter as much as the Arctic-wide total. Thoman found that the minimum extent in the Pacific Arctic seas off Alaska, the Chukchi and Beaufort, has shown a flat trend over the past 15 years without a sustained recovery. At this year's minimum, the ice edge sat far north of its 1980s position from the East Siberian Sea to the Beaufort Sea, though some thicker multiyear ice persisted not far north of Alaska's northeast coast. Both the Northern Sea Route along Russia and the Northwest Passage through the Canadian Arctic were open in late summer, which rarely happened in the 20th century.

Those changes reach Alaskans directly. Open water late in the season can leave coastlines more exposed to fall storms before shore ice forms, affect travel and hunting on the ice, and change conditions for marine mammals such as walruses and ice seals that rest on it. Longer open-water seasons also allow more ship traffic in remote waters with little spill-response or rescue infrastructure.

NASA's announcement did not attribute any specific feature of this year's melt season to climate change, and scientists note that year-to-year swings are heavily shaped by weather, including winds, clouds and storms.

Readers can follow conditions through NSIDC's Sea Ice Index. Alaskans concerned about fall coastal storms should watch forecasts and coastal flood alerts from the National Weather Service.

Antarctic Ice Peaks After an Unusual Dip

Antarctic sea ice tracked near record-low levels for most of this year's growth season, NSIDC said. In August, the ice around Antarctica shrank by roughly 116,000 square miles (300,000 square kilometers) over six days before resuming its seasonal growth, according to NASA. Meier said the drop appeared to be driven by weather that pushed and compacted thin, mobile ice at the outer edge, and he called its size unusual even though such swings are common.

Antarctic sea ice varies more from year to year than Arctic ice because it is not hemmed in by land and responds more freely to wind and weather. The annual maximum has generally been lower in recent years, but Boisvert and Meier remain cautious about calling that a long-term trend because of the region's large natural variability. The maximum usually arrives in late September or early October and has occurred as early as Aug. 30, so NASA and NSIDC will confirm it only after seasonal growth has clearly ended.

The satellite record behind these findings began with NASA's Nimbus-7 satellite in October 1978 and continues today with the AMSR2 instrument aboard the Japan Aerospace Exploration Agency's GCOM-W satellite. A NASA animation of this year's Arctic melt shows the ice retreating from mid-March to Sept. 12.

The bottom line: Arctic sea ice ended the 2026 melt season tied for 10th-lowest on record, extending a two-decade plateau at historically low levels, while Antarctic sea ice likely peaked at its third-lowest maximum. Both findings are preliminary, and NSIDC's full analysis is expected in early October.

What Readers Want to Know

How small did Arctic sea ice get this year?

It reached its annual minimum on Sept. 12 at about 1.78 million square miles (4.60 million square kilometers), according to NASA and NSIDC.

Is this a record low?

No. It tied 2008, 2010, and 2025 for the 10th-lowest minimum since satellite records began in late 1978. The record low was set on Sept. 17, 2012.

Is Arctic sea ice recovering?

No. The minimum has leveled off since about 2007, but at a much lower level than in earlier decades. This year's minimum is still nearly 15% below any year before 2007.

Why do some sources rank it differently?

Different datasets use different methods, and several recent minimums are nearly identical. NSIDC ranks 2026 tied for 10th, some analyses of the same data place it 11th, and Europe's OSI SAF index ranks it 14th.

What is happening with Antarctic sea ice?

NSIDC's preliminary analysis indicates it most likely peaked on Sept. 14 at about 6.79 million square miles, which would be the third-lowest maximum on record if confirmed.

What did the minimum look like near Alaska?

The ice edge sat far north of its 1980s position off Alaska, and the minimum extent in the Chukchi and Beaufort Seas has shown no sustained recovery over the past 15 years.