From The Science Matters

By Ron Clutz

The arctic ice extents are now fully reported for January 2026, showing refreezing rates fluctuating, likely due to a wavy polar vortex sending cold Arctic air to sub-arctic latitudes and replacing it with warmer southern air.

From AER Polar Vortex blog:

As seen in Figure iii (and also Figure 12) the PV has an elongated shape in appearance for much of the next two weeks in contrast to the more circular PV of early January. The PV has a “split” appearance this week and into next week, a character trait or signature of a more extreme stretched PV. I think the more extreme nature of the stretched PV is consistent with the model forecasts of extreme cold in the US and even potential snowstorms. But then at least in this animation there is a clear PV split with two distinct and independent PV centers.

Figure iii. Forecasted average 10 mb geopotential heights (dam; contours) and geopotential height anomalies (m; shading) across the Northern Hemisphere for 19 Jan 2026 and forecasted from 20 Jan 2026 to 03 Feb 2026. The forecasts are from the 00Z 19 Jan 2026 GFS model ensemble.

The chart below shows the 20-year averages for Arctic ice extents in January along with 2026 and 2025, as well as SII v.4.

Note MASIE 2025 started 5 to 600k km2 (or half a Wadham) below the 20-year average, but by day 12 cut the deficit to 151k km2, or a gap of 1%. Freezing rate went flat for a week before recovering and ending the month nearly 14M km2, 365k id deficit or 3%.  SII v.4 tracked lower than MASIE throughout January, averaging ~200k km2 lower for the month. The chart below shows the distribution of ice extent across the Arctic regions on January 31, 2026.

Region	2026031	Average Day 31	2026-Ave.	2025031	2026-2025
(0) Northern_Hemisphere	13954044	14319064	-365020	13543739.54	410305
(1) Beaufort_Sea	1071070	1070419	651	1071000.73	69
(2) Chukchi_Sea	966006	965975	31	965989.12	17
(3) East_Siberian_Sea	1087137	1087067	70	1087137.23	0
(4) Laptev_Sea	897845	897825	20	897844.8	0
(5) Kara_Sea	923456	917599	5857	921519.96	1936
(6) Barents_Sea	582372	556751	25621	428814.24	153558
(7) Greenland_Sea	663996	613445	50551	614788.59	49207
(8) Baffin_Bay_Gulf_of_St._Lawrence	1027979	1315356	-287378	1080930.32	-52952
(9) Canadian_Archipelago	854931	853582	1349	854877.96	53
(10) Hudson_Bay	1260870	1260784	86	1260903.34	-33
(11) Central_Arctic	3202511	3210553	-8042	3211378.6	-8867
(12) Bering_Sea	670583	642788	27795	534452.21	136131
(13) Baltic_Sea	114996	61637	53359	39333.65	75663
(14) Sea_of_Okhotsk	549996	809973	-259977	559692	-9696

The table shows that most regions are close to the 20-year average.  Two major deficits are in Baffin Bay and Sea of Okhotsk, partly offset by several smaller surpluses.