National Snow and Ice

Northern Hemisphere Snow and Ice

Approximately 16 percent of the contiguous U.S. (CONUS) was covered by snow at the beginning of March, according to NOAA's National Snow Analysis. Snow covered the mountainous West as well as areas from the upper Great Lakes to the Northeast. Over the first week of March storms delivered snow from the middle Rockies to the upper Mississippi Valley, and CONUS snow coverage increased to a peak of 31.9 percent on March 8, before decreasing to 9.3 percent on March 28. Another system late in March brought snow to parts of the northern Plains and into the Northern Great Lakes, bringing snow coverage across CONUS to 19 percent on March 31. A comparison of the total season-to-date snowfall (October–March) with the average for the same period shows above-average snowfall across parts of the mountainous West, central Plains, Gulf Coast, Southeast and Ohio Valley, while below-average seasonal snowfall was evident across parts of the southern Sierras, Great Basin, southern Rockies, northern Plains, Upper Midwest and portions of the Northeast Atlantic Coast.

According to NOAA data analyzed by the Rutgers Global Snow Lab, the March snow cover extent was 525,500 square miles, 218,000 square miles below the 1991-2020 average, and the eighth-lowest value in the 59-year satellite record. Snow cover was below-average across much of the CONUS, including the southern Rockies, the central and northern Plains, across the Mid-Atlantic and Northeast. Regions of above-average snow cover were limited to some parts of the Cascades, Sierras and northern Rockies, along with the northern Great Lakes region.

Melting of winter and spring mountain snowpack provides a crucial summer water source across much of the western United States. The total annual water budget for agriculture and human use in the mountainous West is highly dependent on the amount of snow melt that will occur in spring and is proportional to the amount of snow on the ground, which can be approximated by a measure of the snow water equivalent (SWE).

On February 28, SWE values were below normal across much of the central and southern Sierras, southern Rockies, the northern Coast Range and northern Cascades, the Columbia Plateau and northern Bitterroots. Above-normal SWE values were present across the southern Cascades, southern Bitterroots and parts of the northern Great Basin, central Rockies and northern Plains. By the end of March, SWE values had increased across the Sierras, returning to near-normal levels for the northern and central parts of the range, and above-normal for much of the central Great Basin. The northern Cascades continued to have below-normal SWE, while much of the southern Cascades, parts of the northern Great Basin, the Blue Mountains and southern Bitterroots were above to much-above normal. The southern and northern Rockies continue to have below-normal SWE while the middle Rockies continue to be near to above normal.