Monthly Arctic sea extent in September of 2025 ranks eleventh lowest on record

The chart shows the monthly average Arctic sea ice extent in million square kilometers, capturing the strong seasonal cycle. March and September -- the months of the highest and lowest ice conditions -- are highlighted.

September 2025 tied for the 10th lowest extent on record on a daily basis, rather than the monthly mean basis shown here. The National Snow and Ice Data Center recently changed its satellite data source for calculating Arctic sea ice extent, which has led to small changes in the 2025 values shown above for January through June, compared with the prior dataset. 
Chart: Chris MooneySource: National Snow and Ice Data CenterCreated with Datawrapper