I fly weekly out of MHT or BOS all year long, and our weather is about as icky as yours. Just remember that they are not going to take off if conditions are adverse. They are not that foolish. You won't get off the ground in Orlando if the weather is bad in Albany, and if it gets bad while you're in the air, they'll divert you. If it's really cold, they'll de-ice the plane before take-off. That does not mean there is ice, just preventing it.
All told, I would WAY rather be in a plane than in my car during the winter. The airports know how to handle snow & ice much better than the other drivers out there.
So don't worry at all about safety, worry a tiny bit about the schedule, focus on the fun you'll have on vacation.