September 25, 2025: The Arctic sea ice has experienced a larger increase rate for this week of 2.68% (last week’s increase rate was 0.36%), from the level on 09/18/2025 of 4.688 M km² to 4.817 M km² for this week. So, we are now definitely in the sea ice increase season.

The sea ice extent for 2025 to date has now risen by two spots to 10th place for the lowest sea ice extent for this day of the year as noted below when the lowest sea ice extent was at 3.735 M km² on 09/25/2012. 

Ranking of lowest sea ice extent for the day of the post, values in M km² :

2012    3.735
2020    4.212
2007    4.213
2023    4.436
2019    4.470
2024    4.503
2008    4.729
2011    4.748
2018    4.770
2025    4.817

The negative sea ice anomaly this week was greater than the anomaly of -0.78362 M km² on 09/18/2025 to a higher negative anomaly of -0.91083  M km² on 09/25/2025, and so more anomalously negative for this time of year.