Besides the cold, short daylight hours is the other draw-back. If you are camping its a lot of tent time. Average tourist probably only spends 5 or 6 hours in the saddle each day. In the summer those are spread out through the day with lots of time for breaks. Not so in the winter.

I would think that riding south from New jersey on the ACA Atlantic coast route, for instance, would keep you in ocean moderated weather much of the time. Only the occasional hard winter weather there.