It is frigid out! Teeth chattering cold with, at the moment, no end in sight. How are the bees maintaining? The current timeline of Feb 8th as I write this, the bees are in transition. In most colonies the bees have moved up into the top box. Hives that were very heavy with honey going into winter, probably have not moved up because of a more than ample food supply. Consider the late fall and early winter, the temperatures were quite tame. This led to low consumption of food stores, at least in the lower half of MN and WI. Now with the cold blast, bees that are moving up from the lower box may be get caught in a bad spot with little food.
If you remember a post from last fall when I said that the top box should have 8 full frames of honey and one partially filled frame which is located about in the center of the top box. Right now, the current weather is why you wanted that partially filled frame. As the bees move into the top box, they don’t like to walk on cold or frozen honey. This can slow the move up. With the partially filled frame, the bees can easily move up on the empty comb. As the bees are on that partially filled frame, they will be adjacent to frames of honey on either side of the comb that they are on. The bees can now warm the honey on the lower part of the frame. If the bees have already moved up before this cold weather hit. The bees should be fine as long as they are on honey. Bees that have not moved up but are sitting on a frame of honey, they should be ok also, as long as the food holds out.
The last point is the tough one, that may or may not be happening in your hive. The bees are approaching the time when the queen starts laying eggs. If the queen has already started laying, the bees will not leave the brood. If the bees deplete all the food around where they are clustered keeping the brood warm, they will starve. If the bees are caught in a place with diminishing food stores, they might not be able to get to more food.
I paint a bleak picture, that is not my intent. Right now, there is nothing we can do until this cold weather breaks. After this subzero weather passes, beekeepers should go out and try to see if their bees made it. Bees are tough creatures when it comes to cold weather. If they have food, they can survive. If the food is gone, so are the bees.