NOAA's National Centers for Environmental Information
NH Snow Cover Extent
| May 2013 | Snow Cover Extent | Anomaly 1991-2020 | Trend per decade | Rank (47 years) | Record | ||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| million km² | million mi² | million km² | million mi² | million km² | million mi² | Year(s) | million km² | million mi² | |||
| Northern Hemisphere | 16.28 | 6.29 | -1.94 | -0.75 | -0.85 | -0.33 | Largest | 45th | 1974 | 23.09 | 8.92 |
| Smallest | 3rd | 2010 | 15.38 | 5.94 | |||||||
| North America | 9.02 | 3.48 | -0.02 | -0.01 | -0.22 | -0.08 | Largest | 29th | 1974 | 11.48 | 4.43 |
| Smallest | 19th | 2010 | 7.80 | 3.01 | |||||||
| Eurasia | 7.26 | 2.80 | -1.92 | -0.74 | -0.63 | -0.24 | Largest | 47th | 1976 | 12.51 | 4.83 |
| Smallest | 1st | 2013 | 7.26 | 2.80 | |||||||
Data Source: Global Snow Laboratory, Rutgers University. Period of record: 1967–2013 (47 years)
The Northern Hemisphere snow cover extent (SCE) during May 2013 was 16.08 million square km (6.21 million square miles), 2.85 million square km (1.10 million square miles) below the 1981-2010 average and the 3rd smallest May snow cover extent on record. May of 2012 and 2010 had smaller SCE for the Northern Hemisphere. During the month, both North America and Eurasia had below-average SCE. For the spring season (March-May), the Northern Hemisphere SCE was slightly above average and ranked as the 22nd smallest (26th largest) spring SCE.
During May, the North American SCE was 260,000 square km (100,000 square miles) below the 1981-2010 average of 9.29 million square km (3.59 million square miles). This was the 20th smallest (28th largest) May SCE for North America. Below-average snow cover was observed across the Rocky Mountains of the U.S. and Canada, the Canadian Prairies, and eastern Canada. Above-average snow cover was observed across much of Alaska, northwestern Canada, and parts of central Canada. For the spring season, the North American SCE was 820,000 square km (316,600 square miles) above the 1981-2010 average and the 10th largest spring SCE on record for North America. It was also the largest spring SCE since 1997.
Eurasian SCE was 7.06 million square km (2.72 million square miles), 2.59 million square km (1.00 million square miles) below the 1981-2010 average. This marked the smallest May SCE for Eurasia on record, dipping below the May SCE of 2012. Below-average snow cover was observed across the Alps, Scandinavia, and all of Russia. Above-average snow cover was observed along parts of the Tibetan Plateau. Spring SCE was 620,000 square km (239,400 square miles) below average and ranked as the 13th smallest spring SCE for Eurasia.
Sea Ice Extent
| May 2013 | Sea Ice Extent | Anomaly 1991-2020 | Trend per decade | Rank (35 years) | Record | ||||
|---|---|---|---|---|---|---|---|---|---|
| million km² | million mi² | Year(s) | million km² | million mi² | |||||
| Northern Hemisphere | 13.00 | 5.02 | +0.54% | -2.32% | Largest | 26th | 1985 | 14.07 | 5.43 |
| Smallest | 10th | 2006 | 12.52 | 4.83 | |||||
| Southern Hemisphere | 10.92 | 4.22 | +6.12% | +2.24% | Largest | 3rd | 2008 | 11.05 | 4.27 |
| Smallest | 33rd | 1980 | 8.86 | 3.42 | |||||
| Ties: 1996, 2000 | |||||||||
| Globe | 23.92 | 9.24 | +3.01% | -0.30% | Largest | 10th | 1982 | 24.73 | 9.55 |
| Smallest | 26th | 2006 | 21.98 | 8.49 | |||||
| Ties: 1998 | |||||||||
Data Source: National Snow and Ice Data Center (NSIDC). Period of record: 1979–2013 (35 years)
According to the National Snow and Ice Data Center (NSIDC), the Northern Hemisphere sea ice extent — which is measured from passive microwave instruments onboard NOAA satellites — averaged for May 2013 was 13.10 million square km (5.06 million square miles), 2.17 percent below the 1981-2010 average, and the 10th smallest May sea ice extent on record. The rate of ice decline in May 2013 was 36,400 square km (14,100 square miles) per day, slower than the average rate of decline for this time of year. Below-average ice was observed on the Atlantic side of the Arctic, while above-average ice was observed on the Pacific side. May Arctic sea ice extent is decreasing at an average rate of 2.3 percent per decade.
The May 2013 Southern Hemisphere sea ice extent was 11.47 million square km (4.43 million square miles), 6.33 percent above the 1981-2010 average and the fifth largest May Antarctic sea ice extent on record. May Southern Hemisphere sea ice extent is increasing at an average rate of 2.2 percent per decade, with substantial interannual variability.
For further information on the Northern and Southern Hemisphere snow and ice conditions, please visit the NSIDC News page.