What is happening in a winter cluster of bees? Beekeepers winter colonies and most of us don't realize the biology of the bees that we are trying to get through the winter. These two links I think explain the what is happening in the cluster and what temperatures are really in the hive. Most beekeepers think if we open a colony in the winter the bees will perish in short order. The graphic clearly shows that the hive temperatures about 9 inches from the cluster, drop to near outside temperatures. The temperatures are in centigrade and there is a Fahrenheit conversion in the charts graphic.
http://westmtnapiary.com/winter_cluster.html This site has a good explanation of honeybees. Check out the other articles on this website.
http://capabees.org/content/uploads/2013/02/winteringpdf.pdf