NH Snow Cover Extent
|November 2021||Snow Cover Extent||1981-2010 Anomaly||Trend
(out of 56 years)
|million km2||million mi2||million km2||million mi2||million km2||million mi2||Year(s)||million km2||million mi2|
Data Source: Global Snow Laboratory, Rutgers University. Period of record: 1966–2021 (56 years)
Snow cover extent for the Northern Hemisphere during November 2021 was above average at 35.45 million square km (13.69 million square miles). Although the snow cover extent for the Northern Hemisphere was above average, it was the smallest snow cover extent since 2013. November 2021 marked the 13th consecutive November with above-average Northern Hemisphere snow cover extent. The Northern Hemisphere snow cover extent during the three-month period of September–November was 810,000 square km 310,000 square miles above average and the 31st largest autumn snow cover extent.
The North America snow cover extent for November 2021 was below-average at 12.93 million square km (4.99 million square miles) and the 13th smallest November snow cover extent in the 54-year record. Above-average snow cover extent was observed across parts of the southern Alaska, southern tier of Canada, and across the northeastern U.S. Meanwhile, below-average snow cover extent was observed across much of the western contiguous U.S. and across parts of central and northeastern Canada. Alaska had an above-average November snow cover extent, resulting in its 10th largest November snow cover extent on record. Meanwhile, Canada and the contiguous U.S. had below-average snow cover extent, with Canada having its eighth smallest November extent and the U.S. had its 23rd smallest November extent. During the autumn season (September–November), the North America snow cover extent was slightly below average at 260,000 square km (100,000 square miles).
In Eurasia, above-average snow cover extent was observed across much of Scandinavia, southern Russia, Kazakhstan, Mongolia, and northeastern and northwestern China. Meanwhile, below-average November snow cover extent was observed across much of southeastern Europe, western Russia, as well as part of southern China. Overall, the average Eurasian November snow cover extent was 2.0 million square km (790,000 square miles) above average and the ninth largest for November on record. Eurasia's autumn snow cover extent was also above average and the 19th largest September–November period on record.
Sea Ice Extent
The sea ice extent data for the Arctic and Antarctic are provided by the National Snow and Ice Data Center (NSIDC) and are measured from passive microwave instruments onboard NOAA Satellites. The sea ice extent period of record is from 1979–2021 for a total of 43 years.
|November 2021||Sea Ice Extent||
(out of 43 years)
|million km2||million mi2||Year(s)||million km2||million mi2|
Data Source: National Snow and Ice Data Center (NSIDC). Period of record: 1979–2021 (43 years)
During the month, sea ice extent grew faster than average. By the end of the month, the monthly average Arctic sea ice extent was 9.77 million square km (3.77 million square miles) or 930,000 square km (359,000 square miles) below average. This tied with 2009 and 2011 as the ninth smallest November sea ice extent on record. November 2021 marked the 22nd consecutive November with below-average Arctic sea ice extent.
The Antarctic sea ice extent during November 2021 was 950,000 square km (370,000 square miles) below average and was the second smallest November sea ice extent on record. Only November 2016 had a smaller sea ice extent. Five of the six smallest November Antarctic sea ice extents have occurred since 2016. According to the NSIDC, sea ice extent was below average in the Bellingshausen and Weddell seas.