Here in New England there isn't much you can do for your bees during the winter months, except worry over whether they'll survive. Especially now, with near-zero temperatures and over 4 feet of recent snow, I'm certainly not going to open the hives.
But I've noticed a reassuring sign: There are little valleys in the snow right around the hives. It's not just drifting. You can tell there's a source of heat there. Which means a decent-sized colony is still alive.
(BTW don't worry; they have top entrances. The snow hasn't got that high-- yet.)
I would consider adding insulation around the hives next year. If the heat is making it through the hive wall, then they have to work that much harder to keep it warm inside.