Same here.
Started last May.
Strong through fall.
Flying in a warm spell first week January.
Dead after a brutal cold snap two weeks later.
A lot of people here in MA lost their bees.
I imagine extreme temperature variations are hard on bees. Perhaps you could buy some of that 2 inch thick hard foam insulation and build boxes with a few small openings to put over the hives when the weather goes extreme. I think the 2 inch ones are R13