Not a lot. For me anyway. Biggest thing is finding people to go along especially if they don't dive dry. What is even more of an issue is the shorter daylight hours. There's a site less than an hour away from me, shallow but good for practice. Problem is there are no lights at all other than what you bring with you. Summer I solo it once a week or so. Winter byt the time I get off work and get there it's dark when I get out of the water, I mean really dark in the woods no streetlights type stuff. Kinda dangerous exiting and if it's icy forget it. THe one lake is two hours away, never freezes, and is warm relative to air temps but again short days and the fact that it's at altitude and you can go in for an hour dive and come up to 2 inches of fresh snow on the ground in a blizzard slows people down as well. Otherwise cold itself is not an issue.