Lake Winnipeg, Lake Manitoba and Lake Winnipegosis in Manitoba historically have seen lake-effect snow as early as late October, and it is common throughout early to mid-November. Towards the end of November, the lakes sufficiently cool and begin to freeze, ending the lake-effect snow. A brief period of lake-effect snow is also common near Great Bear Lake and Great Slave Lake in the Northwest Territories during early winter (usually early to mid-October); the lake-effect season for both lakes is very short, though. The lakes are frozen roughly eight months of the year, and as a result, have very little time to warm during the summer.