The weather in Michigan is unpredictable for the most part. The winters can get really cold and will often be below freezing. If you're not used to this type of weather, don't worry—nobody can get used to it, except for those guys that are from the area and like to pretend they're not cold when they walk to class in shorts and a t-shirt when there is a blizzard outside.
Michigan tends to see a lot of thunderstorms and tornado warnings. Sometimes there's a lot of snow or ice and CCS will have a snow day, but don't count on it. They usually stay open no matter what. However, the Winter 2010 semester experienced a couple snow days. There seems to be more wind than some other areas, but it's still nothing compared to Chicago.