Winter in Alaska lasts different amounts of time depending on the location.  In Anchorage, where I live, we see the first snowfall in late October or so.  Cold and snow here lasts through late April/early May when we experience Spring "break up"...when the snow melts and everything turns into a muddy mess.  Other parts of the state see their snowfall start earlier or later, depending on physical location in the state, proximity to the coastlines, etc.