You don't mention the area in which you live, and the conditions you'll be riding in. I have found that the bike itself should be chosen for the riding conditions, moreso than the weather. Off-road single track? Rail-to-Trail? Gravel? Pavement? City/community streets?
I personally have a hybrid, which suits my needs perfectly well for most all of the places I ride. Nothing too gnarly. I can ride it year-round on roads, woodland trails, etc., as long as there is no snow (and I'm wearing the appropriate clothing).