I am near Brandon Manitoba Canada and minus 40F (equal to minus 40C) is quite normal for a few weeks each winter.
The bees get out for "cleansing flights" on warmer days. I have made insulating boxes of 1 1/2 inch styrofoam. This year our honey is from Canola which granulates quickly. Apparently the bees can suck the moisture out and leave the dry sugary stuff behind and then starve.
My question: other than feeding sugar water or corn syrup, how can I keep them safe? What temp will keep honey from granulating? The upper brood box right now weighs 90 lbs. (40 Kg)