This weekend it will be warm enough to check the hives to see if they are alive or dead. You need to check. You are not letting "the heat out of the hive". We put package bees in a hive when it is in the 30's.
Bee suppliers start filling up with bee orders and checking now will make sure you can get a bee order in.
Don’t pull frames. You are looking to make sure there is capped honey near the cluster of bees. If you don’t see bees on top of the top box, look down deep between the frames and see if the bees are there. If you only see a frame or two of bees on top, there is a possibility that the whole cluster has not moved up yet from the lower box. If you are unsure, remove the winter cover and break the top box loose. Teeter the top box back and look between the two boxes. If you see no bees and you only had two frames up on top, I would order a new package of bees because that hive is going nowhere. If there is a big cluster under the top box, try to determine that there is honey near the cluster. The queen should be laying now and the bees can't move away from the brood. Also, if you tip that top box back, you should be able to tell if the box is heavy with honey. Right now you want to see at least three frames full of honey in the top box.
Here is a YouTube video I made about checking a hive in February.