SIO (Sea Ice Outlook) July 2026 report shows the predicted September average Arctic Ice Extent from various contributors to the Sea Ice Prediction Network (SIPN) before the actual September monthly extent is reported by NOAA Sea Ice Index (SII). The report (link in red) gave this overview.

2026: July Report from Sea Ice Prediction Network

Pan-Arctic Extent Forecasts

The July 2026 Outlook received 23 pan-Arctic September sea ice extent contributions (Figure 1), with a median of 4.45 million square kilometers and an interquartile range of 4.20 to 4.67 million square kilometers. We received 12 statistical/ML based predictions for pan-Arctic September sea ice extent. The statistical models have a median of 4.44 million square kilometers and an interquartile range of 4.30 to 4.55 million square kilometers (Figure 2). There are nine dynamical model contributions. The dynamical models have a median forecast of 4.47 million square kilometers with an interquartile range of 4.15 to 4.75 million square kilometers, over twice the range of statistical forecasts. Last year’s observed September extent (4.75 million km2) is at the high end of the dynamical forecasts, and higher than all but one of the statistical forecasts (Figure 2).

Above are predictions as of Mid-July for the September 2026 monthly average ice extent reported by NOAA Sea Ice Index (SII). This post provides a look at the 2026 September monthly averages comparing MASIE and SII datasets. (20-year average is 2007 to 2026 inclusive).

SIP network predicted SII would be 4.45M km2, and the actual result is 4.81M, while MASIE reported 5.04M km2.

The table below provides the monthly Arctic ice extent averages for comparisons (all are M km2)

Monthly	MASIE 2026	SIIv.4 2026	MASIE–SII	MASIE–20yr AVE	SIIv.4–20yr AVE
Jan	11.365	11.222	0.143	-2.395	-2.355
Feb	13.322	13.107	0.215	-1.315	-1.319
Mar	14.348	14.098	0.250	-0.484	-0.558
Apr	13.601	13.569	0.032	-0.482	-0.432
May	12.173	12.151	0.022	-0.437	-0.504
June	10.543	10.422	0.121	-0.257	-0.426
July	8.045	7.708	0.338	-0.224	-0.309
Aug	6.009	5.563	0.446	0.136	-0.034
Sept	5.041	4.810	0.230	0.334	0.113

The first two data columns are the 2026 YTD shown by MASIE and SII, with the MASIE surpluses in column three.  Column four shows MASIE 2026 compared to MASIE 20 year averages, while column five shows SII 2026 compared to SII 20 year averages.   MASIE started the year with sizable deficits to average then recovered in steadily spring and summer to surpass average in August, and now 334k km2 above average. SII was also well below its averages throughout and much lower than MASIE in August, that gap reduced to -230k km2 in September.

Current Arctic Ice Extent Conditions

The September average month shows the annual dip in arctic ice extents, then recovering to end slightly higher than the beginning.  Note MASIE 2026 started 350k km2 above average and ended 595k in surplus. SII v.4 began 629k km2 in deficit to MASIE, then gained steadily closing the gap, ending only .053k lower.

The table below shows the distribution of ice over the Arctic regions yesterday September 30, 2026, in comparison with the MASIE average and some other years of note.

Region	2026273	Day 273 Ave.	2026-Ave.	2007273	2026-2007
(0) Northern_Hemisphere	5531029	4963064	567965	4086883	1444146
(1) Beaufort_Sea	732729	547541	185188	498743	233986
(2) Chukchi_Sea	421657	228860	192797	51	421606
(3) East_Siberian_Sea	389374	309478	79897	311	389063
(4) Laptev_Sea	236581	171732	64850	235245	1337
(5) Kara_Sea	18	34515	-34497	15367	-15349
(6) Barents_Sea	0	12802	-12802	4851	-4851
(7) Greenland_Sea	270410	236177	34232	353210	-82801
(8) Baffin_Bay_Gulf_of_St._Lawrence	57131	56398	733	42247	14883
(9) Canadian_Archipelago	420912	371062	49850	307135	113777
(10) Hudson_Bay	16	3155	-3139	1936	-1921
(11) Central_Arctic	3001059	2990096	10963	2626511	374548

The massive surpluses in Eurasian basins of Chukchi, E. Siberian, Laptev, along with Beaufort and Canadian achipelago, more than offset small deficits in Atlantic basins Kara and Barents seas. The over surplus was 568k km2 or 11%, and exceeded 2007 by 1.4 wadhams of ice extents.

Summary

The experts involved in SIPN expected SII 2026 September to be somewhat lower than recent years, but Arctic ice extents greatly exceeded the 20 year averages.

Footnote:

Some people unhappy with the higher amounts of ice extent shown by MASIE continue to claim that Sea Ice Index is the only dataset that can be used. This is false in fact and in logic. Why should anyone accept that the highest quality picture of ice day to day has no shelf life, that one year’s charts can not be compared with another year? Researchers do this, including Walt Meier in charge of Sea Ice Index. That said, I understand his interest in directing people to use his product rather than one he does not control. As I have said before:

MASIE is rigorous, reliable, serves as calibration for satellite products, and continues the long and honorable tradition of naval ice charting using modern technologies. More on this at my post Support MASIE Arctic Ice Dataset

MASIE: “high-resolution, accurate charts of ice conditions”
Walt Meier, NSIDC, October 2015 article in Annals of Glaciology.