Figure 12. (a) Predicted 10 mb geopotential heights (dam; contours) and temperature anomalies (°C; shading) across the Northern Hemisphere averaged for 25 Nov to 29 Nov 2025. (b) Same as (a) except forecasted averaged from 05 Dec to 09 Dec 2025. The forecasts are from the 00Z 24 November 2025 GFS model ensemble.

The polar vortex is pronounced this year, resulting in warmer temperature over the Arctic ocean, and slowing the normal sea ice recovery.  Dr. Judah Cohen at AER Arctic Oscillation blog provides information like the chart above.

After a pattern of solidly growing sea ice extent in October, a slowdown occurred in November, coincidental with the warm spots shown above.  The graph below shows 2025 compared to the 19 year average (2006 to 2024 inclusive), to SII (Sea Ice Index) and some notable years.

According to MASIE. the average November adds ~2.5M km2 of sea ice extent, which is matched also by 2007.  2024 started below average, but gained steadily to close the gap.  2025 started at the same level, but the refreezing slowed down, ending November in deficit by 1.1M km2.  SII shows even lower ice extents (the last two days not yet reported.)

The table below shows the distribution of ice in the Arctic Ocean basins, suggesting two places where ice recovery is lagging.

Overall ice extent was 1.1M km2 below average or 10%.  About half the deficit comes from the European Atlantic basins, Kara and Barents seas.  The other half is mostly from N. America’s Hudson and Baffin bays. Ice in these regions operate on the LIFO principle, last in and first out.

At this point in the year, Arctic ice has grown back to 65% of last March maximum with 2.5 months to catch up.   AER  suggests that things may shift again in December:

Figure 9. Forecasted surface temperature anomalies (°C; shading) from 05 Dec to 09 Dec 2025. The forecasts are from the 00Z 24 Nov 2025 GFS ensemble.

Figure 10. Forecasted snowfall (mm/day; shading) from 05 Dec to 09 Dec 2025. The forecasts are from the 00Z 24 Nov 2025 GFS ensemble.

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.

The animation shows the rapid growth of Arctic ice extent during October 2025, from day 274 to day 304, yesterday.  For all of the fuss over the September minimum, little is said about Arctic ice growing 3M km2, that’s 3 Wadhams in one month!.  Look on the left (Russian side) at the complete closing of the Northern Sea Route for shipping.

The graph below shows 2025 compared to the 19 year average (2006 to 2024 inclusive), to SII (Sea Ice Index) and some notable years.

This year October added 2.6M km2 from end of September compared to an average October increase of 3.4M km2.  The first two weeks were above average, before the refreezing rate slowed down ending in a deficit of ~0.5M km2.  In other terms the end of October ice extents were four days behind the average, according to MASIE.  SII started the same, but tracked lower in the second half of October.

The table below shows the distribution of ice in the Arctic Ocean basins.

Overall ice extent was 534k km2 below average or 6%.  Surpluses appear on the Eurasian shelf seas of Beaufort, Chukchi and East Siberian, while sizeable deficits are shown elsewhere on the Atlantic side, especially Kara, Baffin Bay, Canadian Archipelago and Central Arctic.

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.

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.

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.)

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.

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.

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:

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.

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.

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.)

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.

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.

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:

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.

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.

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.)

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.

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.

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:

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.

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. Now mid-August MASIE shows the Arctic ice extent matching the 19-year average.

During this period the average year loses ~2.4M km2 of ice extent.   MASIE on day 197 was 287k km2 down, and the gap increased to 460k km2 by July 27 (day 208). In August 2025 the melt rate slowed, erasing the deficit to average the last 3 days. Note 2007 and 2024 were ~200k km2 below average mid-August.  Meanwhile SII v.4 is showing much lower ice extents than previously, ranging from -200k km2 to -550k km2 below MASIE extents.

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.)

The table shows large surpluses in Eurasian basins  Beaufort, Chukchi and E. Siberian, offset by deficits in Central Arctic, Kara and Greenland seas. Hudson Bay is mostly open water at this time of year. 2025 exceeds the ice extents in 2020 by 720k km2.

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.

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:

Postscript Re. SII v.4

Update: Strange Sea Ice Data July End 2025

Update August 2, 2025

NSDIC acknowledged my query regarding the SII (Sea Ice Index) dataset, which is described below.  While awaiting an explanation I have 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 below shows the implications for July as an example.

You can see how v.4 in red is lower than v.3 in orange throughout the month.  It may be that v.3 values will no longer be reported in the future, though that has not been confirmed to me.  It should also be noted that v.3 values for 2024 and prior years have also been altered in v.4 and I intend to look into that impact.

Note:  After comparisons of monthly averages, results from the two versions appear comparable for previous years. 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.

Overview

Before presenting the MASIE and SII results for July, a note about a strange thing in today’s Sea Ice Index report.  I have sent a note to them requesting an explanation for why the values have been altered from those in the dataset just two days ago.  When attempting to add into my spreadsheets the final two July days, I noticed that all the previous values were now different.  Exploring further, going back to beginning of 2024 all values had changed, some showing larger extents and many showing smaller ice extents than previous recorded.

For 2024 the new values added ice extents with the average day gaining slightly (47k km2).  But in 2025 so far, the average day lost (-57k km2) compared to the values two days ago.  Curiously, since March 14, 2025 all days had lower values at a daily rate of -75k km2.  In sum, the altered values in 2025 removed ~11M km2 of ice extents so far, and 10M km2 of that since March 14.  In the report below, I excluded the altered SII values awaiting news from NSIDC.

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. The chart shows the July Arctic ice extents on average decline from 9.7M to 6.9M km2. MASIE started July ~5M km2 in deficit to average and ended the month ~4M km2 down, continuing to melt about four days in advance of the average decline. SII matched MASIE the first half of July, then tracked slightly lower the second half.

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.)

The table shows  most regions in deficit with Kara the largest, and Canadian Archipelago and Central Arctic also sizable.  Hudson Bay and Greenland Sea will lose the rest of their ice in upcoming weeks. Surpluses in Beaufort and Chukchi offset about 220k km2 of losses elsewhere.

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 NH and Tropics Lead UAH Temps Lower May 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:

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 Arctic ice extents and NH snow cover.

Before presenting the MASIE and SII results for July, a note about a strange thing in today’s Sea Ice Index report.  I have sent a note to them requesting an explanation for why the values have been altered from those in the dataset just two days ago.  When attempting to add into my spreadsheets the final two July days, I noticed that all the previous values were now different.  Exploring further, going back to beginning of 2024 all values had changed, some showing larger extents and many showing smaller ice extents than previous recorded.

For 2024 the new values added ice extents with the average day gaining slightly (47k km2).  But in 2025 so far, the average day lost (-57k km2) compared to the values two days ago.  Curiously, since March 14, 2025 all days had lower values at a daily rate of -75k km2.  In sum, the altered values in 2025 removed ~11M km2 of ice extents so far, and 10M km2 of that since March 14.  In the report below, I excluded the altered SII values awaiting news from NSIDC.

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. The chart shows the July Arctic ice extents on average decline from 9.7M to 6.9M km2. MASIE started July ~5M km2 in deficit to average and ended the month ~4M km2 down, continuing to melt about four days in advance of the average decline. SII matched MASIE the first half of July, then tracked slightly lower the second half.

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.)

The table shows  most regions in deficit with Kara the largest, and Canadian Archipelago and Central Arctic also sizable.  Hudson Bay and Greenland Sea will lose the rest of their ice in upcoming weeks. Surpluses in Beaufort and Chukchi offset about 220k km2 of losses elsewhere.

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 NH and Tropics Lead UAH Temps Lower May 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:

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 Arctic ice extents and NH snow cover.