Because Southwestern Ontario is surrounded by water on three sides, many parts of Southwestern and Central Ontario get a large part of their winter snow from lake-effect snow. This region is notorious for the whiteouts that can suddenly reduce highway visibility on North America’s busiest highway (Ontario Highway 401) from clear to zero. The region most commonly affected spans from Port Stanley in the west, the Bruce Peninsula in the north, Niagara-on-the-Lake to the east, and Fort Erie to the south. The heaviest accumulations usually happen in the Bruce Peninsula, which is between Lake Huron and Georgian Bay. So long as the Great Lakes are not frozen over, the only time the Bruce Peninsula does not get lake-effect snow is when the wind is directly from the south.