For lake-effect rain or snow to form, the air moving across the lake must be significantly cooler than the surface air (which is likely to be near the temperature of the water surface). If not, then it falls as lake-effect rain. If the air temperature is low enough to keep the precipitation frozen, it falls as lake-effect snow. Under certain conditions, strong winds can accompany lake-effect snows creating blizzard-like conditions however, the duration of the event is often slightly less than that required for a blizzard warning in both the US and Canada. Lake-effect blizzards are the blizzard-like conditions resulting from lake-effect snow. These include areas east of the Great Lakes in North America, the west coasts of northern Japan, the Kamchatka Peninsula in Russia, and areas near the Great Salt Lake, Black Sea, Caspian Sea, Baltic Sea, Adriatic Sea, and North Sea. The areas affected by lake-effect snow are called snowbelts. This uplifting can produce narrow but very intense bands of precipitation, which deposit at a rate of many inches of snow each hour, often resulting in a large amount of total snowfall. The effect is enhanced when the moving air mass is uplifted by the orographic influence of higher elevations on the downwind shores. The same effect also occurs over bodies of saline water, when it is termed ocean-effect or bay-effect snow. The vapor then freezes and is deposited on the leeward (downwind) shores.

The lower layer of air, heated up by the lake water, picks up water vapor from the lake and rises up through the colder air above. Lake-effect snow is produced during cooler atmospheric conditions when a cold air mass moves across long expanses of warmer lake water.

A cold northwesterly to westerly wind over all the Great Lakes created the lake-effect snowfall of January 10, 2022.

Watch snowfall