Briefing on Arctic sea ice minimum and Antarctic sea ice maximum report - September 2026

Summary

• Arctic sea ice reached a minimum of 5.06 million sq km on 12th September, the 14th lowest in the satellite record (since 1979).
• Antarctic sea ice reached a maximum extent to date of 18.12 million sq km on 11th September; if not subsequently exceeded this would be the 3rd lowest in the satellite record. However, Antarctic sea ice maxima have in the past been recorded as late as early October and so it remains possible that a higher maximum will be recorded.

Arctic sea ice minimum

Arctic sea ice reached a minimum extent of 5.06 million sq km on 12^th September according to the OSI SAF Sea Ice Index (Aaboe et al., 2026). This was 1.51 million sq km below the 1981-2010 average minimum, and was the 14^th lowest in the satellite record (since 1979). It was 0.75 million sq km above the long-term linear trend (Figure 1).[*]

Figure 1. Timeseries of annual minimum Arctic sea ice extent over the era of satellite observations, with long-term linear trend indicated.

Extent at minimum was well below average in all parts of the Arctic Ocean, with only small regions of near-average ice extent in the Greenland Sea, eastern Beaufort Sea, and central Laptev Sea (Figure 2).

Figure 2. Arctic sea ice extent on 12^th September 2026, with 1981-2010 average extent indicated in orange, and the regions referred to in the text labelled. Data are from EUMETSAT OSI SAF (Baordo et al., 2023).

Antarctic sea ice maximum

As of 20^th September, Antarctic sea ice had reached a maximum extent of 18.12 million sq km, recorded on 11^th September, following which ice extent has decreased somewhat (Figure 3). If not subsequently exceeded, this would represent the third-lowest maximum in the satellite era, after 17.53 and 17.65 million sq km in 2023 and 2024 respectively. However, many years have seen maxima recorded after 20^th September, so it remains possible that a higher value may still be recorded for this year.

Figure 3. Daily Antarctic sea ice extent for 2026, compared with recent years, selected historic years with relatively low ice cover, and the 1981-2010 average, with interquartile and interdecile ranges indicated by the shaded areas. Data are from the OSI SAF Sea Ice Index (Aaboe et al., 2026).

Sea ice extent on 11^th September was rather high in the Bellingshausen and Weddell Seas surrounding the Antarctic Peninsula, but somewhat below normal elsewhere, except for an unusual ‘arm’ of sea ice extending north from the Ross Sea (Figure 4).

Figure 4. Antarctic sea ice extent on 11^th September 2026, with 1981-2010 average extent indicated in orange, and the regions referred to in the text labelled. Data are from EUMETSAT OSI SAF (Baordo et al., 2023).

References

Aaboe, S., Lavergne, T., Sørensen, A. and Eastwood, S. (2026) OSI SAF Sea ice index 1978-onwards, Product OSI-420-a, Version 3.0, April 2026, Available at: Sea-Ice Index, version 3.0 | OSI SAF. Date Accessed: 21-09-2026.

Baordo, F., Vargas, L. F. and Howe, E. (2023) OSI SAF Global Sea Ice Concentration (AMSR), Product OSI-408-a, Version 1.2, June 2023. Available at: Global Sea-Ice Concentration (AMSR2) | OSI SAF. Date Accessed: 21-09-2026.

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[*] Note that according to the NSIDC Sea Ice Index, an alternative widely used dataset, the 2026 sea ice minimum is the 11th lowest since 1979 and is 1.63 million sq km below the 1981-2010 average. The difference is due to a number of years' sea ice minima being very close together. It is also due to the sea ice minimum being particularly sensitive to small differences in how sea ice coverage is estimated from the microwave data received by satellites.