Tag: MASIE

2026 Mid-May: Arctic Ice Extents Less Impacted by Vortex

The arctic ice extents are now reported through Mid-May 2026, and as noted previously the wavy polar vortex has hampered ice formation with incusions of warmer southern air into the Arctic circle.

From Science Matters

By Ron Clutz

The arctic ice extents are now reported through Mid-May 2026, and as noted previously the wavy polar vortex has hampered ice formation with incusions of warmer southern air into the Arctic circle.  This was still a factor early in May, but now appears to be receding, according to the AER Polar Vortex blog (May 11).

Judah Cohen:  As I discussed in the previous blog, I do think that the influence from the PV did continue into easrly May, and in fact May so far has been impressively cool in Eastern Canada and the Eastern and less so in parts of Europe (see Figure ii). With more Greenland blocking predicted (see Figure i) is that still the influence of the PV?

Figure ii. Estimate of the observed surface temperatures (°C; shading) from 01 May to 10 May 2026 based on GFS initializations and the GFS forecast from the 11May 2026 run.

From Figure 11, it appears that the influence of the PV split/Final Warming has ended this week with cold/negative polar cap height standardized geopotential height anomalies (PCHs) throughout the stratosphere and tropsophere. Last week I used the PCH limited to the North Atlantic sector to argue the ongoing influence of the PV split and today’s plot (see Figure iii) does not provide any longer an alternative interpretation but rather any further influence of the PV will have to wait until next fall. Though I think this does need to be qualified as my interpretation rather than being fully objective.

The chart below shows the 20-year averages for Arctic ice extents from Mid-April to Mid-May March along with 2026, 2025 and 2006 as well as SII v.4.

Remarkably the deficit to average opened up on May 5 (day 125) to 739k km2, but since then the gap was cut in half, reaching 328k km2 at the end of this period.  The 20-year average maximum daily ice extent loss over this period is 1.5M km2, and in 2026 the decline was 1.2M km2. These are MASIE stats, but SII shows virtually the same results.

The table below shows the distibution of ice extents on day 136 across regions of the Arctic ocean.

Region2026136Day 136 Ave.2026-Ave.20061362026-2006
 (0) Northern_Hemisphere1227140112599588-32818812157814113586
 (1) Beaufort_Sea107107010471012396910661394931
 (2) Chukchi_Sea94074292724013502956734-15992
 (3) East_Siberian_Sea10654751081524-160501074876-9402
 (4) Laptev_Sea872186878598-6412889990-17804
 (5) Kara_Sea9170178739444307383956977448
 (6) Barents_Sea344186411348-67162182554161632
 (7) Greenland_Sea549259621605-7234651933729922
 (8) Baffin_Bay_Gulf_of_St._Lawrence9170901054954-13786589233524755
 (9) Canadian_Archipelago8531778416401153782880624370
 (10) Hudson_Bay1176685117200746771071342105343
 (11) Central_Arctic32125023223772-11270316922543277
 (12) Bering_Sea248490285726-37236478464-229973
 (13) Baltic_Sea05749-574915239-15239
 (14) Sea_of_Okhotsk101440172136-70695168615-67174

The table shows that most regions are close to or above the 20-year average.  The majority of the 3% overall deficit is from Baffin Bay, down 138k km2,  Smaller deficits are in Okhotsk, Barents and Greenland seas.  All of those regions will be nearly ice-free end of summer.

Illustration by Eleanor Lutz shows Earth’s seasonal climate changes. If played in full screen, the four corners present views from top, bottom and sides. It is a visual representation of scientific datasets measuring ice and snow extents.

2026 March Arctic Ice Recovery Slowed by Vortex

The arctic ice extents are now reported through end of March 2026, the month whose average is taken as the annual maximum. As noted previously the wavy polar vortex has hampered ice formation with incusions of warmer southern air into the Arctic circle.

From Science Matters

By Ron Clutz

The arctic ice extents are now reported through end of March 2026, the month whose average is taken as the annual maximum. As noted previously the wavy polar vortex has hampered ice formation with incusions of warmer southern air into the Arctic circle. This may be changing according to the most recent image from AER PV blog.

Figure 12. Observed 10 mb geopotential heights (dam; contours) and temperature anomalies (°C; shading) across the Northern Hemisphere averaged from 17 Mar. (b) Same as (a) except forecasted averaged from 28 Mar to 1 Apr 2026. The forecasts are from the 00Z 17 Mar 2026 GFS ensemble.

Remarkably, the 2025 annual daily extent maximum of 14.48M km2 was on day 73 of that year.  Arctic ice reached 14.55 on day 63 in 2026, and continued near that level until day 74, before starting the usual decline.

The chart below shows the 20-year averages for Arctic ice extents for March along with 2026, 2025 and 2006 as well as SII v.4.

The 20-year average maximum daily ice extent appears at 14.93M km2 on day 71 before starting to decline. MASIE 2006 and 2026 started this period the same and tracked each other until 2026 ended higher by ~200k km2, and slightly above 2025.

The table below shows the distibution of ice extents on day 90 across regions of the Arctic ocean.

Region2026090Day 90 Average2026-Ave.20060902026-2006
 (0) Northern_Hemisphere1414910114587351-43825013913402235699
 (1) Beaufort_Sea1071070107027979110686832387
 (2) Chukchi_Sea96600696432516819590916915
 (3) East_Siberian_Sea1087137108630982810846272510
 (4) Laptev_Sea89784589713570989777371
 (5) Kara_Sea930404918948114569221648240
 (6) Barents_Sea582189653649-71460623912-41723
 (7) Greenland_Sea569080667067-97988604935-35856
 (8) Baffin_Bay_Gulf_of_St._Lawrence14037371384371193661026934376804
 (9) Canadian_Archipelago85493185334915828516913240
 (10) Hudson_Bay126088712555545333124038920498
 (11) Central_Arctic32230203234756-117363241074-18054
 (12) Bering_Sea819147705446113701662863156284
 (13) Baltic_Sea3685560091-23235129348-92492
 (14) Sea_of_Okhotsk433109826350-393242588167-155058

The table shows that most regions are close to or above the 20-year average.  The majority of the 3% overall deficit is from Sea of Okhotsk, down ~400k km2,  Smaller deficits are in Barents and Greenland seas, partly offset by a surplus in Bering sea. All of those regions will be nearly ice-free end of summer.

As for the March Monthly Averages, here is the history:

Illustration by Eleanor Lutz shows Earth’s seasonal climate changes. If played in full screen, the four corners present views from top, bottom and sides. It is a visual representation of scientific datasets measuring ice and snow extents.

Vortex Slows Arctic Ice Recovery 2026 February End

The arctic ice extents are now reported through February 2026, early on showing rising refreezing rates bringing Arctic ice extents within 200k km2 of the 20-year average. In the last 2 weeks the wavy Polar Vortex pushed cold south and replaced it with warmer southern air. Remarkably, Arctic ice reached 14.44 on day 43 in 2026, virtually matching the 2025 annual daily extent maximum of 14.48M km2 on day 80 of that year.

From Science Matters

By Ron Clutz

The arctic ice extents are now reported through February 2026, early on showing rising refreezing rates bringing Arctic ice extents within 200k km2 of the 20-year average.  In the last 2 weeks the wavy Polar Vortex pushed cold south and replaced it with warmer southern air.   Remarkably, Arctic ice reached 14.44 on day 43 in 2026, virtually matching the 2025 annual daily extent maximum of 14.48M km2 on day 80 of that year.

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

As stated previously, likely due to a wavy polar vortex, MASIE 2026 grew rapidly in February reaching 14.52 M km2 on day 51, surpassing the 2025 max of 14.48 on day 80.  In the last week the extent dropped back down to 14.4 M. Sea Ice Index (SII v4) reported lower extents than MASIE in February, averaging -250k km2 on a daily basis.

The vortex temperature shifts are shown below in charts from AER AO/PV blog.

Figure 12. (a) Observed 10 mb geopotential heights (dam; contours) and temperature anomalies (°C; shading) across the Northern Hemisphere for 17 Feb 2026. (b) Same as (a) except forecasted averaged from 28 Feb to 4 Mar 2026. The forecasts are from the 00Z 17 Feb 2026 GFS ensemble. Source: AER AO/PV blog.

The table below shows the distibution of ice extents on day 59 across regions of the Arctic ocean.

Region2026059Day 59 Average2026-Ave.20250592026-2025
 (0) Northern_Hemisphere1438409414861155-47706114000679383416
 (1) Beaufort_Sea10710701070420650107100169
 (2) Chukchi_Sea96600696547353396598917
 (3) East_Siberian_Sea108713710871112710871370
 (4) Laptev_Sea89784589783788978450
 (5) Kara_Sea914161922224-8062925512-11351
 (6) Barents_Sea567312604234-36922361405205907
 (7) Greenland_Sea73161962790810371163796193658
 (8) Baffin_Bay_Gulf_of_St._Lawrence12649921512995-2480041357658-92666
 (9) Canadian_Archipelago854931853573135885487853
 (10) Hudson_Bay126087012604933771260903-33
 (11) Central_Arctic31451103209967-648573159772-14663
 (12) Bering_Sea72411565901065105577908146207
 (13) Baltic_Sea13617592656435184057595599
 (14) Sea_of_Okhotsk7378151057674-319858774415-36599

The table shows that most regions are close to or above the 20-year average.  Two major deficits are in Baffin Bay and Sea of Okhotsk, partly offset by several smaller surpluses, mostly in Greenland Sea, Baltic and Bering seas. The overall 2026 MASIE deficit is 3% of the 20-year average.

Arctic Ice Nearly Average mid-February 2026

The arctic ice extents are now reported through mid-February 2026, showing rising refreezing rates bringing Arctic ice extents within 200k km2 of the 20-year average.  Remarkably, the last two days virtually matched the 2025 annual extent maximum of 14.48M km2 on day 80 of that year, compared to 14.44 on day 43 in 2026.

From Science Matters

By Ron Clutz

The arctic ice extents are now reported through mid-February 2026, showing rising refreezing rates bringing Arctic ice extents within 200k km2 of the 20-year average.  Remarkably, the last two days virtually matched the 2025 annual extent maximum of 14.48M km2 on day 80 of that year, compared to 14.44 on day 43 in 2026.

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

As stated previously, likely due to a wavy polar vortex, MASIE 2026 refroze slowly in January reaching a deficit of 622k km2 on day 26.  Since then, ice grew at a higher rate, ending this period 176k km2 below average, or 1% down. Note that compared to day 44 last year, 2026 ice is more than half a Wadham greater, 656k km2.  And as mentioned above, 2025 will not match yesterday until day 80. Note SII v.4 tracks lower than MASIE throughout, on average in deficit by 242K km2.

Region2026044Average day 442026-Ave.20250442026-2025
 (0) Northern_Hemisphere1442748114603337-17585613771518.64655962
 (1) Beaufort_Sea107107010703846861071000.7369
 (2) Chukchi_Sea966006965785222965989.1217
 (3) East_Siberian_Sea1087137108713251087137.230
 (4) Laptev_Sea8978458978387897844.80
 (5) Kara_Sea93502390943725586911762.3723261
 (6) Barents_Sea64960656642183185434920.5214686
 (7) Greenland_Sea772110625671146439635758.41136351
 (8) Baffin_Bay_Gulf_of_St._Lawrence10402951429059-3887641335264.28-294969
 (9) Canadian_Archipelago8549318535311399854877.9653
 (10) Hudson_Bay126087012605952761260903.34-33
 (11) Central_Arctic32359303204874310563195022.3340907
 (12) Bering_Sea68976967151218256333643.58356125
 (13) Baltic_Sea155657889906666635593.84120063
 (14) Sea_of_Okhotsk742439914421-17198272046221977

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

Arctic Ice Aplenty at Annual Dip September 2025

After a sub-par March maximum, by end of May 2025 Arctic ice closed the gap with the 19-year average.  In mid-August MASIE showed the Arctic ice extent matching the 19-year average.  Mid month Arctic ice went above average and remained in surplus, ranging from a high of +231k km2 to +160k km2 at end of August. Now during the annual minimum month of September 2025 there is  Arctic ice aplenty.

A serene Arctic landscape featuring large icebergs and floating ice on calm water, under a clear blue sky.

From Science Matters

By Ron Clutz

After a sub-par March maximum, by end of May 2025 Arctic ice closed the gap with the 19-year average.  In mid-August MASIE showed the Arctic ice extent matching the 19-year average.  Mid month Arctic ice went above average and remained in surplus, ranging from a high of +231k km2 to +160k km2 at end of August. Now during the annual minimum month of September 2025 there is Arctic ice aplenty.

Line graph showing Arctic ice extents from August to September 2025, compared with 19-year averages and previous years, illustrating changes in ice levels over the days.

During the annual dip in Arctic ice extent, the average year since 2006 is lowest on day 260 at 4.53M km2.  It then rises to 4.8M km2 ten days later.  The cyan line shows 2025 above average throughout, its lowest extent at 4.85M km2 on day 265, and now up to 5.07M km2.  SII v.4 was lower than MASIE throughout, but has drawn closer in recent days.  So far MASIE September average is 5.0M and SII is 4.7M, with 4 more days remaining in the month. Note 2007 was ~800k km2 in deficit, 2020 ~600k down at day 270, while last year was ~300k below average.

The regional distribution of ice extents is shown in the table below. (Bering and Okhotsk seas are excluded since both are now virtually open water.)

Region2025270Day 270 ave.2025-Ave.20072702025-2007
 (0) Northern_Hemisphere5074777479875827601840235691051207
 (1) Beaufort_Sea483527520730-372034820301497
 (2) Chukchi_Sea332213210352121861214331999
 (3) East_Siberian_Sea499915280923218992311499604
 (4) Laptev_Sea27343115279412063623834035091
 (5) Kara_Sea490633680-2877415113-10207
 (6) Barents_Sea012945-129454851-4851
 (7) Greenland_Sea165160225916-60756339720-174560
 (8) Baffin_Bay_Gulf_of_St._Lawrence7028447480228044362426660
 (9) Canadian_Archipelago302771336303-3353328036022410
 (10) Hudson_Bay241522521631936479
 (11) Central_Arctic29385882974115-355272615795.38322792

The table shows large surpluses in Eurasian basins  Laptev, Chukchi and E. Siberian, more than offsetting smaller deficits in Central Arctic, CAA and Greenland seas. Hudson Bay is mostly open water at this time of year. 2025 exceeds the average ice extents by 276k km2, or 6%, and is over 1 wadham greater than 2007 or a surplus of 1.05M km2 of ice extent.

September monthly average ice extent is considered the annual minimum for climate purposes.  Note also that typically the lowest daily value occurs mid-September, with a small positive gain between the end of August and end of September.

A detailed map of the Arctic region showing various seas, basins, and ridges, labeled with names like Canada Basin, Beaufort Sea, and Greenland Sea.

Why is this important?  All the claims of global climate emergency depend on dangerously higher  temperatures, lower sea ice, and rising sea levels.  The lack of additional warming prior to 2023 El Nino is documented in a post SH Drives UAH Temps Cooler July 2025.

Line graph depicting UAHv6 Global TLT air temperature anomalies alongside CO2 levels, showing trends from 1995 to 2025.

The lack of acceleration in sea levels along coastlines has been discussed also.  See Observed vs. Imagined Sea Levels 2023 Update

Also, a longer-term perspective is informative:

Graph illustrating post-glacial sea level rise with markers indicating various regions and events over thousands of years.

Footnote Regarding  SII v.4

NSDIC acknowledged my query regarding the SII (Sea Ice Index) dataset. While awaiting an explanation I investigated further. My last download of the SII Daily Arctic Ice Extents was on July 30, meaning that the most recent data in that file was day 210, July 29. The header on that file was Sea_Ice_Index_Daily_Extent_G02135_v3.

Then on August 1, the downloaded file had the heading Sea_Ice_Index_Daily_Extent_G02135_v4. So it appears that these are now the values from a new version of SII. As I wrote in my query, since March 14 all of the values for Arctic Ice Extents are lower in this new record. The graph above shows the implications for August as an example of estimates from SIIv.4.

In the past, SIIv.3 tracked MASIE with slightly lower values.  But with v.4, larger monthly average deficits to MASIE were reported in July 2025 ( -282k km2) and in August (-440k km2).

The change started in January 2025 and will be the basis for future reporting.  The logic for this is presented in this document: Sea Ice Index Version 4 Analysis

In June 2025, NSIDC was informed that access to data from the Special Sensor Microwave
Imager/Sounder (SSMIS) onboard the Defense Meteorological Satellite Program (DMSP)
satellites would end on July 31 (NSIDC, 2025). To prepare for this, we rapidly developed version
4 of the Sea Ice Index. This new version transitions from using sea ice concentration fields
derived from SSMIS data as input to using fields derived from the Advanced Microwave
Scanning Radiometer 2 (AMSR2) sensor onboard the Global Change Observation Mission – W1
(GCOM-W1) satellite.  On 29 July 2025, we learned that the Defense Department decision to terminate access to DMSP data had been reversed and that data will continue to be available until September 2026.

We are publishing Version 4, however, for these reasons:

• The SSMIS instruments are well past their designed lifespan and a transition to
AMSR2 is inevitable. Unless the sensors fail earlier, the DoD will formally end the
program in September 2026.
• Although access of SSMIS will continue through September 2026, the Fleet
Numerical Meteorology and Oceanography Center (FNMOC), where SSMIS data
from the DMSP satellite are downloaded, made an announcement that “Support
will be on a best effort basis and should be considered data of opportunity.” This
means that SSMIS data will likely contain data gaps.
• We have developer time to make this transition now and may not in the future.
• We are confident that Version 4 data are commensurate in accuracy to those
provided by Version 3.

A digitally edited image featuring a prominent glacier in the background and a man with a perplexed expression in the foreground, accompanied by speech bubbles discussing a prediction about ice disappearance.

September 2025 Arctic Ice Outlook

After the dip there will be continuing recovery of ice extent, with end of September usually higher than the beginning.  The September monthly average will be interesting to compare.

A scenic view of a glacial landscape featuring large blue ice formations in the foreground, with a glacier and mountainous terrain in the background under a grey sky.

From Science Matters

By Ron Clutz

Bar graph displaying July 2025 SIO Arctic predictions by various contributors, showing statistical and dynamical model outputs with observed values for 2024.
Figure 1. Distribution of SIO contributions for July estimates of September 2025 pan-Arctic sea-ice extent. Public/citizen contributions include Sun.

2025: July Report from Sea Ice Prediction Network

The July 2025 Outlook received 22 pan-Arctic contributions (Figure 1). This year’s median forecasted value for pan-Arctic September sea-ice extent is 4.27 million square kilometers with an interquartile range of 4.13 to 4.54 million square kilometers. This is lower than observed in 2023 (4.37 million square miles) and 2024 (4.35 million square miles) observed in September. The lowest sea-ice extent forecast is 3.38 million square kilometers, from Sun, which would be a new record low for the satellite period (1979-present); the highest sea-ice extent forecast is 5.17. . . The observed extent values are from the NSIDC Sea Ice Index (Fetterer et al., 2017), based on the NASA Team algorithm sea ice concentration fields distributed by the NASA Snow and Ice Distributed Active Archive Center (DAAC) at NSIDC (DiGirolamo et al., 2022; Meier et al., 2021). 

These are predictions as of August 20 for the September 2025 monthly average ice extent reported by NOAA Sea Ice Index (SII). This post provides a look at the 2025 Year To Date (YTD) based on monthly averages comparing MASIE and SII datasets. (19-year average is 2006 to 2024 inclusive).

Line graph showing Arctic monthly ice extents for 2025 year-to-date, comparing MASIE 2025, Silv.4 2025, MASIE 19-year average, and MASIE data for 2007 and 2012, with measurements in million square kilometers across the months from January to December.

The graph puts 2025 into recent historical perspective. Note how 2025 was slightly below the 18-year average for the first 3 months, then tracked closely to average through August. The outlier 2012 provided the highest March maximum as well as the lowest September minimum, coinciding with the Great Arctic Cyclone that year.  2007 began the period with the lowest minimum except for 2012.  SIIv.4 2025 tracked closely to MASIE the first 6 months, then dropped lower July and in August 459k km2 below MASIE 2025 and also lower than 2007 and 2012.

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

MonthlyMASIE 2025SIIv.4 2025MASIE -SIIMASIE-19yr AVESIIv.4-19yr AVE
Jan13.20613.1310.075-0.583-0.470
Feb13.80213.7450.057-0.878-0.715
Mar14.27414.1400.134-0.587-0.545
Apr13.84613.910-0.063-0.249-0.109
May12.49712.559-0.062-0.119-0.108
June10.51010.4850.025-0.306-0.388
July7.9427.6600.282-0.345-0.375
Aug5.8545.3950.459-0.020-0.220

The first two data columns are the 2025 YTD shown by MASIE and SII, with the MASIE surpluses in column three.  Column four shows MASIE 2025 compared to MASIE 19 year averages, while column five shows SII 2025 compared to SII 19 year averages.  YTD August MASIE started the year in deficits to average but recovered in spring to virtually match average in August. SII was below its averages throughout and much lower than MASIE in July, and in August down by nearly half a Wadham.

Current Arctic Ice Extent Conditions

Line graph comparing Arctic ice extents over time, showing data for the years 2007, 2020, 2024, 2025, along with 19-year averages. The y-axis represents ice extents in million square kilometers, while the x-axis denotes days of the year.

This 30 day period shows the annual dip in arctic ice extents, the daily lowest value coming on or about day 250, ten days from now. Currently MASIE shows Arctic ice tracking well above average with a surplus of 235k km2 yesterday.  Both 2007 and 202 were much below average, while 2024 nearly average at the minimum.  SIIv.4 has been reporting lower extents, in the range of 300 to 400k km2 less than MASIE, yesterday a deficit of 367k km2.

After the dip there will be continuing recovery of ice extent, with end of September usually higher than the beginning.  The September monthly average will be interesting to compare.

Summary

The experts involved in SIPN are expecting SII 2025 September to be somewhat lower than recent years.  The way MASIE is going, this September looks to be above its average, and much higher than SII.  While the daily minimum for the year occurs mid September, ice extent on September 30 is typically close to the ice extent on September 1.

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

A gold seal of approval featuring a star in the center and laurel leaves, with a blue ribbon at the bottom displaying the text 'SEAL OF APPROVAL'.

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

Surplus Arctic Ice Persists to End of August 2025

After a sub-par March maximum, by end of May 2025 Arctic ice closed the gap with the 19-year average. Then in June the gap reopened and in July the melting pace matched the average, abeit four days in advance of average. In mid-August MASIE showed the Arctic ice extent matching the 19-year average.  Mid-month Arctic ice went above average and remained in surplus, ranging from a high of +231k km2 to +160k km2 at end of August.

Stunning icebergs floating in a calm, reflective Arctic water under a soft sunrise, showcasing intricate shapes and textures of ice.

From Science Matters

By Ron Clutz

After a sub-par March maximum, by end of May 2025 Arctic ice closed the gap with the 19-year average. Then in June the gap reopened and in July the melting pace matched the average, abeit four days in advance of average. In mid-August MASIE showed the Arctic ice extent matching the 19-year average.  Mid-month Arctic ice went above average and remained in surplus, ranging from a high of +231k km2 to +160k km2 at end of August.

Line graph depicting Arctic ice extents for August, showing data from multiple years with a focus on 2025, 2024, 2023, and average extents over 19 years. The Y-axis represents ice extents in million square kilometers, while the X-axis represents days of the year.

During August the average year loses 1.9M km2 of ice extent.  MASIE on day 213 was 308k km2 down, and the gap closed steadily, going into surplus on day 230. Note 2020 and 2024 were well  below average mid-August.  2024 ended nearly average, while 2020 went down almost off the chart. Meanwhile SII v.4 started August ~400k km2 lower than MASIE, increasing to -690k mid month, before drawing closer to MASIE (-200k km2) on the last reported day 242. More on what happened to SII in footnote.

The regional distribution of ice extents is shown in the table below. (Bering and Okhotsk seas are excluded since both are now virtually open water.)

Region2025243Day 243 Ave.2025-Ave.20202432025-2020
 (0) Northern_Hemisphere511237249522491601234345398766974
 (1) Beaufort_Sea64654656990976637763281-116735
 (2) Chukchi_Sea400517284622115895212438188079
 (3) East_Siberian_Sea563058360155202902176996386062
 (4) Laptev_Sea172574175114-25401029171545
 (5) Kara_Sea257948983-4640423958-21379
 (6) Barents_Sea015952-1595200
 (7) Greenland_Sea106688167723-61035192361-85673
 (8) Baffin_Bay_Gulf_of_St._Lawrence610342765633378501656019
 (9) Canadian_Archipelago278943298169-192262731165827
 (10) Hudson_Bay860420611-1200623611-15007
 (11) Central_Arctic28702792982526-1122472672903.81197375

The table shows large surpluses in Eurasian basins  Beaufort, Chukchi and E. Siberian, more than offsetting deficits in Central Arctic, Kara and Greenland seas. Hudson Bay is mostly open water at this time of year. 2025 exceeds the average ice extents by 160k km2, or 3%, and is 767k km2 greater than 2020, or nearly 0.8 Wadhams of ice extent.

September monthly average ice extent is considered the annual minimum for climate purposes.  Note also that typically the lowest daily value occurs mid-September, with a small positive gain between the end of August and end of September.

A detailed map of the Arctic region, highlighting various seas and basins such as the Canada Basin, Beaufort Sea, and Chukchi Sea, with topographical features labeled in yellow.

Why is this important? 

All the claims of global climate emergency depend on dangerously higher temperatures, lower sea ice, and rising sea levels. 

The lack of additional warming prior to 2023 El Nino is documented in a post SH Drives UAH Temps Cooler July 2025.

Graph showing UAHv6 global temperature anomalies alongside CO2 levels over time, with blue data points indicating temperature changes and a pink line representing CO2 concentrations.

The lack of acceleration in sea levels along coastlines has been discussed also.  See Observed vs. Imagined Sea Levels 2023 Update

Also, a longer-term perspective is informative:

Graph illustrating post-glacial sea level rise over thousands of years, highlighting natural and man-made contributions to sea level changes.

Footnote Regarding  SII v.4

NSDIC acknowledged my query regarding the SII (Sea Ice Index) dataset. While awaiting an explanation I investigated further. My last download of the SII Daily Arctic Ice Extents was on July 30, meaning that the most recent data in that file was day 210, July 29. The header on that file was Sea_Ice_Index_Daily_Extent_G02135_v3.

Then on August 1, the downloaded file had the heading Sea_Ice_Index_Daily_Extent_G02135_v4. So it appears that these are now the values from a new version of SII. As I wrote in my query, since March 14 all of the values for Arctic Ice Extents are lower in this new record. The graph above shows the implications for August as an example of estimates from SIIv.4.

In the past, SIIv.3 tracked MASIE with slightly lower values.  But with v.4, larger monthly average deficits to MASIE were reported in July 2025 ( -282k km2) and in August (-440k km2).

The change started in January 2025 and will be the basis for future reporting.  The logic for this is presented in this document: Sea Ice Index Version 4 Analysis

In June 2025, NSIDC was informed that access to data from the Special Sensor Microwave
Imager/Sounder (SSMIS) onboard the Defense Meteorological Satellite Program (DMSP)
satellites would end on July 31 (NSIDC, 2025). To prepare for this, we rapidly developed version
4 of the Sea Ice Index. This new version transitions from using sea ice concentration fields
derived from SSMIS data as input to using fields derived from the Advanced Microwave
Scanning Radiometer 2 (AMSR2) sensor onboard the Global Change Observation Mission – W1
(GCOM-W1) satellite.  On 29 July 2025, we learned that the Defense Department decision to terminate access to DMSP data had been reversed and that data will continue to be available until September 2026.

We are publishing Version 4, however, for these reasons:

• The SSMIS instruments are well past their designed lifespan and a transition to
AMSR2 is inevitable. Unless the sensors fail earlier, the DoD will formally end the
program in September 2026.
• Although access of SSMIS will continue through September 2026, the Fleet
Numerical Meteorology and Oceanography Center (FNMOC), where SSMIS data
from the DMSP satellite are downloaded, made an announcement that “Support
will be on a best effort basis and should be considered data of opportunity.” This
means that SSMIS data will likely contain data gaps.
• We have developer time to make this transition now and may not in the future.
• We are confident that Version 4 data are commensurate in accuracy to those
provided by Version 3.

A comic featuring a man with a skeptical expression in front of melting ice, with speech bubbles discussing predictions about ice disappearance.

Surplus Arctic Ice late August 2025

After a sub-par March maximum, by end of May 2025 Arctic ice closed the gap with the 19-year average. Then in June the gap reopened and in July the melting pace matched the average, abeit four days in advance of average. In mid-August MASIE showed the Arctic ice extent matching the 19-year average. Now with a week to go Arctic ice has been above average for the last five days, by over +200k km2 yesterday.

A serene Arctic landscape featuring icebergs and floating ice pieces in a calm body of water under a clear blue sky.

From Science Matters

By Ron Clutz

After a sub-par March maximum, by end of May 2025 Arctic ice closed the gap with the 19-year average. Then in June the gap reopened and in July the melting pace matched the average, abeit four days in advance of average. In mid-August MASIE showed the Arctic ice extent matching the 19-year average. Now with a week to go Arctic ice has been above average for the last five days, by over +200k km2 yesterday.

Line graph depicting August Arctic ice extents from 2007 to 2025, showing the comparison to 19-year averages with labeled axes for days and ice extents in million square kilometers.

During August the average year loses 1.9M km2 of ice extent.  MASIE on day 213 was 308k km2 down, and the gap closed steadily, going into surplus on day 230. Note 2020 and 2024 were well below average mid-August.  2024 ended nearly average, while 2020 went down almost off the chart. Meanwhile SII v.4 started August ~400k km2 lower than MASIE, increasing to 600k km2 yesterday.  More on what happened to SII in footnote.

The regional distribution of ice extents is shown in the table below. (Bering and Okhotsk seas are excluded since both are now virtually open water.)

Region2025234Ave. Day 2342025-Ave.20202342025-2020
 (0) Northern_Hemisphere566522354522802129424947191718032
 (1) Beaufort_Sea912878636530276349802063110815
 (2) Chukchi_Sea4560783822047387338251273565
 (3) East_Siberian_Sea597683465057132626248241349443
 (4) Laptev_Sea210514216232-571836330174184
 (5) Kara_Sea353370094-6656123616-20083
 (6) Barents_Sea018103-18103342-342
 (7) Greenland_Sea124456195018-70562227692-103236
 (8) Baffin_Bay_Gulf_of_St._Lawrence6337040548228221306350308
 (9) Canadian_Archipelago3714603485072295435678314677
 (10) Hudson_Bay2111134968-1385835329-14218
 (11) Central_Arctic29025903043900-141310282055082040

The table shows large surpluses in Eurasian basins  Beaufort, Chukchi and E. Siberian, more than offsetting deficits in Central Arctic, Kara and Greenland seas. Hudson Bay is mostly open water at this time of year. 2025 exceeds the average ice extents by 212k km2, or 4%, and is 718k km2 greater than 2020, or 0.7 Wadhams of ice extent.

A detailed topographic map of the Arctic region, highlighting various bodies of water and sea basins such as the Canada Basin, Beaufort Sea, and Laptev Sea, with labeled geographical features.

Why is this important?  All the claims of global climate emergency depend on dangerously higher  temperatures, lower sea ice, and rising sea levels.  The lack of additional warming prior to 2023 El Nino is documented in a post SH Drives UAH Temps Cooler July 2025.

Graph showing UAHv6 Global TLT Air Temperatures (land + ocean), with anomalies in Celsius plotted over time, including CO2 levels measured at Mauna Loa.

The lack of acceleration in sea levels along coastlines has been discussed also.  See Observed vs. Imagined Sea Levels 2023 Update

Also, a longer-term perspective is informative:

Graph showing post-glacial sea level rise with markers indicating locations and changes in sea level over thousands of years.

Footnote Regarding  SII v.4

NSDIC acknowledged my query regarding the SII (Sea Ice Index) dataset. While awaiting an explanation I investigated further. My last download of the SII Daily Arctic Ice Extents was on July 30, meaning that the most recent data in that file was day 210, July 29. The header on that file was Sea_Ice_Index_Daily_Extent_G02135_v3.

Then on August 1, the downloaded file had the heading Sea_Ice_Index_Daily_Extent_G02135_v4. So it appears that these are now the values from a new version of SII. As I wrote in my query, since March 14 all of the values for Arctic Ice Extents are lower in this new record. The graph above shows the implications for August as an example of estimates from SIIv.4

The change started in January 2025 and will be the basis for future reporting.  The logic for this is presented in this document: Sea Ice Index Version 4 Analysis

In June 2025, NSIDC was informed that access to data from the Special Sensor Microwave
Imager/Sounder (SSMIS) onboard the Defense Meteorological Satellite Program (DMSP)
satellites would end on July 31 (NSIDC, 2025). To prepare for this, we rapidly developed version
4 of the Sea Ice Index. This new version transitions from using sea ice concentration fields
derived from SSMIS data as input to using fields derived from the Advanced Microwave
Scanning Radiometer 2 (AMSR2) sensor onboard the Global Change Observation Mission – W1
(GCOM-W1) satellite.  On 29 July 2025, we learned that the Defense Department decision to terminate access to DMSP data had been reversed and that data will continue to be available until September 2026.

We are publishing Version 4, however, for these reasons:

• The SSMIS instruments are well past their designed lifespan and a transition to
AMSR2 is inevitable. Unless the sensors fail earlier, the DoD will formally end the
program in September 2026.
• Although access of SSMIS will continue through September 2026, the Fleet
Numerical Meteorology and Oceanography Center (FNMOC), where SSMIS data
from the DMSP satellite are downloaded, made an announcement that “Support
will be on a best effort basis and should be considered data of opportunity.” This
means that SSMIS data will likely contain data gaps.
• We have developer time to make this transition now and may not in the future.
• We are confident that Version 4 data are commensurate in accuracy to those
provided by Version 3.

A humorous image depicting a glacier with a man making a skeptical expression. The text bubbles suggest a misinterpretation of predictions regarding ice disappearance, referencing 2013 and 2016.

September Outlook Arctic Ice 2023

The experts involved in SIPN are expecting SII 2023 September to be higher than 2007 and somewhat lower than 2022.  The way MASIE is going, this September looks to be nearly average unless some bad weather intervenes.  While the daily minimum for the year occurs mid September, ice extent on September 30 is typically slightly higher than on September 1.

From Science Matters

By Ron Clutz

2023: August Report from Sea Ice Prediction Network

The August median forecasted value for pan-Arctic September sea-ice extent is 4.60 million square kilometers with interquartile values of 4.35 and 4.80 million square kilometers, while individual forecasts range from 2.88 to 5.47 million square kilometers. We note that the lowest two forecasts predict a new record September sea-ice extent value (current record is September 2012, with a sea-ice extent of 3.57 million square kilometers), but these forecasts are outliers relative to the other contributions.

These are predictions for the September 2023 monthly average ice extent as reported by NOAA Sea Ice Index (SII). This post provides a look at the 2023 Year To Date (YTD) based on monthly averages comparing MASIE and SII datasets. (17 year average is 2006 to 2022 inclusive).

The graph puts 2023 into recent historical perspective. Note how 2023 was slightly below the 17-year average for the first 5 months, then recovered to match average in May and has maintained or exceeded average through August. The outlier 2012 provided the highest March maximum as well as the lowest September minimum, coinciding with the Great Arctic Cyclone that year.  2007 began the period with the lowest minimum except for 2012.  SII 2023 was running below MASIE except for May/Juneand is currently just below MASIE 2007 and 2012.

The table below provides the numbers for comparisons (all are M km2)

MonthlyMASIE 2023SII 2023MASIE -SIIMASIE 2023-17 YR AVESII 2023-17 YR AVEMASIE 2023-2007
Jan13.57913.3470.232-0.207-0.250-0.183
Feb14.48114.1770.304-0.207-0.292-0.171
Mar14.65514.4400.215-0.212-0.2480.032
Apr13.97913.992-0.013-0.120-0.0250.283
May11.86612.159-0.293-0.742-0.492-0.561
June11.04410.9630.0810.2420.0990.218
July8.4318.1830.2480.1520.1500.439
Aug5.8255.5610.264-0.062-0.0830.241

The first two columns are the 2023 YTD shown by MASIE and SII, with the MASIE surpluses in column three.  Column four shows MASIE 2023 compared to MASIE 17 year average, while column five shows SII 2023 compared to SII 17 year average.  YTD August both MASIE and SII are very slightly below average. The last column shows MASIE 2017 holding an August surplus of 241k km2 over 2007.

Summary

The experts involved in SIPN are expecting SII 2023 September to be higher than 2007 and somewhat lower than 2022.  The way MASIE is going, this September looks to be nearly average unless some bad weather intervenes.  While the daily minimum for the year occurs mid September, ice extent on September 30 is typically slightly higher than on September 1.

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.