Spring might start in March, but don't let your calendar fool you. Many parts of the United States can still see snow well into April and May.
In fact, there are some cities in the Rockies and the adjacent High Plains that even call April their snowiest month.
Plotted on the map below are various colored shadings, with each color indicating the average date of the season's last measurable snow – defined as an accumulation of at least 0.1 inches – based on the most recent 30-year climatological averages (1991-2020) calculated by NOAA's National Centers for Environmental Information.
While the last measurable snowfall might occur in March for areas closer to the Northeast coast, it can continue to snow until April in much of the interior Northeast.
In fact, some spots in the interior Northeast don't typically see the season's last snow until May, particularly in the higher elevations of northern New England and the Adirondacks of upstate New York.
The average last snowfall is on March 14 in New York City, March 15 in Philadelphia and March 27 in Boston. However, the last 0.1 inches of snow is typically not until early April in Pittsburgh and Syracuse, New York, and late April in Caribou, Maine.
Farther south, in the mid-Atlantic, Washington's average last snow of the season occurs much earlier – on Feb. 27.
The season's last snow generally occurs from late March into April from the Northern Plains to the upper Midwest and the northern Great Lakes.
Chicago averages its last measurable snowfall on March 29, Detroit on April 4 and Minneapolis/St. Paul on April 8. Bismarck, North Dakota, has to wait until April 18 for its last snow in a typical season.
However, the more southern areas of the Midwest tend to see their final 0.1-inch or greater snowfall in March. The average last measurable snow is on March 16 in Indianapolis, March 17 in St. Louis and March 22 in Cincinnati.
Many locations in the Mountain West often see snow well through the spring, with their average last 0.1-inch snowfall occurring in May or even June.
In particular, the Black Hills of South Dakota is a region notorious for very late-season heavy snowstorms. April is the snowiest month in Lead, South Dakota, where 29.2 inches of snow is considered average over the course of that month.
The more populated areas of the West typically see the season's last measurable snow in April or within the first few days of May. For example, Salt Lake City averages its final snowfall on April 16, while Denver's last measurable snow of the season occurs on May 1 in an average year.
Flagstaff, Arizona, one of America's seven snowiest cities, generally sees winter's last gasp on April 23.