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.)