Key figures (as of October 2026)
| September 2026 average extent | 4.81 million km², thirteenth lowest on record |
| Difference from the 1981–2010 September average (6.41 million km²) | 1.60 million km² below |
| Record low September average | 3.57 million km², in 2012 |
| Highest September average in the record | 7.67 million km², in 1980 |
| Long-term September trend, 1979–2026 | -74,100 km² a year, or -11.6% per decade relative to the 1981–2010 average |
| 2026 annual minimum (five-day average) | 4.60 million km² on 12 September, tied for tenth lowest |
| 2026 annual maximum | 14.29 million km² on 15 March, tied with 2025 for the lowest on record |
The measure and how it is published
Sea ice extent is the area of ocean where satellites detect at least 15% ice cover. The official national snow and ice data series records it every day from passive microwave satellite data, and publishes a monthly average for each month, usually within the first days of the following month. A monthly analysis of Arctic conditions, including the September average, is normally released in early October.
Values in the series are reprocessed from time to time as methods and satellite sensors change. From 2025 the series draws on a newer satellite sensor. As a result, some values shown in the current dataset differ from the figures first published. This study resolves on the September 2027 average as first published.
The September record
| Year | Current dataset value (million km²) | Rank in current dataset, lowest first | First-published value (million km²) |
|---|---|---|---|
| 2012 | 3.57 | 1 | 3.61 |
| 2020 | 4.00 | 2 | 3.92 |
| 2023 | 4.38 | 6 | 4.37 |
| 2024 | 4.35 | 4 | 4.38 |
| 2025 | 4.75 | 11 | 4.75 |
| 2026 | 4.81 | 13 | 4.81 |
Current values and ranks as shown in the official monthly dataset updated on 18 October 2026. First-published values as released in early October of each year. The band weights are based on the first-published values, since the forecast resolves on the first-published figure.
Other recent September averages in the current dataset are 4.82 million km² in 2017, 4.79 in 2018, 4.36 in 2019, 4.95 in 2021 and 4.90 in 2022.
Year-to-year swings are large. The September average rose from 3.57 million km² in 2012 to 5.21 million km² in 2013, and fell from 4.90 million km² in 2022 to 4.38 million km² in 2023. Summer weather over the Arctic Ocean, such as cloud cover, winds and storms, drives much of this variation.
The 2026 season
- A record-low winter. The 2026 maximum, 14.29 million km² on 15 March, edged below the 2025 maximum of 14.31 million km², and the two are statistically tied as the lowest in the record. It was 1.36 million km² below the 1981–2010 average.
- A cool, stormy summer. Through most of May, extent tracked close to record low levels. From June the pace of ice loss slowed markedly, as persistent low pressure, cool and cloudy conditions over the Arctic Ocean held back melting, even though global air temperatures were at or near record highs for June to August.
- A mid-ranked minimum. The 2026 minimum, 4.60 million km² on 12 September, tied for tenth lowest with 2008, 2010 and 2025. The last 20 years, from 2007 to 2026, have produced the 20 lowest annual minimum extents in the satellite record.
- A rapid freeze-up. After the minimum, ice grew quickly, and by early October extent had risen into the lower part of the usual range for the date.
Forces pulling extent down
- The long-term trend. September extent has declined by 74,100 km² a year since 1979, or 11.6% per decade.
- Younger, thinner ice. At the end of each melt season since 2007, the extent of ice older than one year has been 1.3 to 1.9 million km², against roughly 3.5 million km² in the 1980s. Since 2012, ice older than four years has covered 250,000 km² or less each year, compared with about 1.5 million km² before 2005. First-year ice melts out more easily in a warm summer.
- Low winter extent. Two record-low maxima in a row give the melt season a head start. A low maximum does not settle the September result on its own, however: the record-low maximum of 2025 was followed by a September average of 4.75 million km².
Forces holding extent up
- Summer weather. A cool, cloudy and stormy summer, as in 2026, can keep the September extent well above the record low, even on a thinner ice cover.
Scenarios: the September 2027 average Arctic sea ice extent
Resolution rule: the September 2027 monthly average Arctic sea ice extent, in million km², from the official national snow and ice data series, as first published, expected in early October 2027. Later reprocessing and revisions do not count. If the published value carries more than two decimals, it is rounded half-up to two decimals before banding: 4.495 counts as 4.50. A value on an edge falls in the higher band: 4.20 is in band 2, 4.50 is in band 3, 4.80 is in band 4 and 5.10 is in band 5. If no September 2027 average has been published by 31 December 2027, the forecast is withdrawn. Probabilities are the Centre's analytical estimates. The forecast is scored with the multi-category Brier score and the ranked probability score, as the bands are ordered.
Below 4.20 million km²
This band covers a very low year, with extent close to or below the 2020 value, and includes a new record below 3.57 million km². It would need a warm, sunny summer with winds that compact the ice, acting on a thin, young ice cover after another low winter. The continuing long-term decline keeps this band real, but only 2012 and 2020 have fallen this low.
4.20 to 4.49 million km²
This band holds the level of 2019, 2023 and 2024. It fits a summer with average to warm conditions over the Arctic Ocean, so that the thin ice cover loses more area than in 2025 and 2026. Several recent years have landed here, which supports a substantial weight.
4.50 to 4.79 million km²
This is the most likely band. It includes the 2025 value of 4.75 million km² and sits just below the 2026 value of 4.81 million km². It matches a year close to the recent average: neither as cool and stormy as 2026 nor as warm as 2020. The weight is the Centre's judgement.
4.80 to 5.09 million km²
This band includes the 2026 value and those of 2017, 2021 and 2022. It would need another summer with cool, cloudy or stormy conditions over the Arctic Ocean. The 2026 result shows that this outcome remains well within reach.
5.10 million km² or more
This band would need the highest September extent since 2014. It would require an unusually cool summer and favourable winds over a larger share of the Arctic Ocean. September averages at this level last occurred in 2009, 2013 and 2014, and the thin ice cover and record-low winters argue against a larger weight.
What to watch
- Monthly averages from the official satellite record: early each month, starting with the October 2026 average in early November 2026.
- The 2027 winter maximum: usually reached in March, with a preliminary announcement in late March 2027.
- The spring and early-summer melt: the pace of ice loss in May, June and July 2027, and how much older, thicker ice survives the winter.
- Summer weather over the Arctic Ocean: air pressure, cloud cover and temperatures from June to August 2027.
- The 2027 annual minimum: usually reached in mid-September, with a preliminary announcement soon after; the September 2027 average follows in early October 2027 (resolves).
Figures as of 30 October 2026. Probabilities are analytical estimates by the Ghaf Centre for Studies & Research.