NH Snow Cover Extent
|January 2021||Snow Cover Extent||1981-2010 Anomaly||Trend
(out of 55 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: 1967–2021 (55 years)
The Northern Hemisphere snow cover extent during January 2021 was 46.77 million square km (18.06 million square miles), which is close to average. January 2021 was characterized by cooler-than-average conditions across much of northern Asia with temperatures at least 2.0°C (3.6°F) below average, while northern North America had temperature departures of at least 3.0°C (5.6°F) above average. For North America, the January 2021 temperature departure of +3.96°C (+7.13°F) was the second highest in the continental 110-year record. Meanhwile, Asia had its coldest January since 2012.
The January North American snow cover extent was 17.65 million square km (6.81 million square miles). This was slightly above the 1981–2010 average at 110,000 square km (40,000 square miles) above average. North American snow cover was above average across parts of the contiguous U.S. Northeast, the Midwest region, as well as parts of the Boston Mountains and the southern Mississippi River region. Below-average snow cover extent was present across parts of the northern Rocky Mountains, parts of the West, and Ohio Valley. The snow cover extent for Canada and the contiguous U.S. during January 2021 was near average. Meanwhile, Alaska's January 2021 snow cover extent tied with five other years as the largest January snow cover extent on record.
Eurasia had a slightly below-average snow cover extent during January 2021 at 29.12 million square km (11.24 million square miles). This is only 200,000 square km (80,000 square miles) below average and the 20th smallest January extent on record. Below-average Eurasian snow cover extent was observed across much of China, southeastern Europe, and parts of southeastern Asia. Above-average snow cover was present across much of Europe, southern Kazakhstan, southern Mongolia, Japan, and across parts of northern China.
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.
|January 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)
The January Arctic sea ice extent was 13.48 million square km (5.20 million square miles), which is 940,000 square km (363,000 square miles) below the 1981–2010 average and the sixth-smallest January in the 43-year record. This was also the 23rd consecutive January with below-average sea ice extent. Baffin Bay had its second-smallest sea ice extent on record, behind January 2011. Arctic sea ice over the Barents, Bering, Greenland, and Kara seas, as well as the Sea of Japan were below average.
The average January Antarctic sea ice extent was 4.67 million square km (1.80 million square miles), which is 330,000 square km (130,000 square miles) below average and tied with 2007 as the 13th smallest January sea ice extent. January 2021 marked the sixth consecutive January with Antarctic sea ice extent below average.