I always cover my hives bottom screens with ply or cardboard if the temp gets below about 40.I have 5 frame mating nucs going right now. The queens should have just emerged. Most are not very well stocked with bees. Yes, I know I should have waited.
What should I do? Wrap with towels? Cover the top and bottom screens with plywood?
I think you'll be the owner of dead hives. You should be feeding them where they are sitting right now.