The snowbelt is a North American region that lies downwind of the Great lakes, where heavy snowfall is common on mostly the eastern and southern shores of the Great Lakes. Lake-effect snow is caused by cold air picking up moisture while crossing the lake and then releasing it as snow when the air cools over land. Throughout much of the winter, lakes produce lake-effect snow and continuously cloudy skies. This phenomenon continues as long as the air temperature is colder than the water temperatures and until the lakes freeze over.

Well-known snowbelts exist southeast of Lake Erie from Cleveland, Ohio to Buffalo, NY and south of Lake Ontario from Rochester, NY to Utica, NY and onwards to Watertown, NY. On the eastern shore of Lake Michigan similar snowbelts are found. Snowbelts also exist in Canada off Lake Superior and Lake Huron. During the winter, NW winds and the lake effect snow causes frequent road closures, especially along Hwy 21 along the north shore of Lake Huron and Hwy 26 around Barrie. The northeastern shores of Lake Ontario are often hit with heavy lake effect snow when SW winds are prevalent.

Lake Erie is the shallowest of the five Great Lakes and is most likely to completely freeze over in winter. This alleviates the problem of heavy lake effect snow for some areas. However, it does not end the probability of other damaging winter storms. In 1977, Buffalo was hit by a wind storm that blew powder snow from Lake Erie into the city, which had frozen earlier than usual. The storm produced little snow of its own.

Other snowbelts exist throughout the world. The west side of the Japanese island of Hokkaido and the western side of Russia’s Kamchatka Peninsula are a few. When the cold winter winds blow outward from Siberia it builds a high pressure system that picks up moisture at sea and then dumps it over land as heavy snowfall.