From Bee Culture Sept 1, 2009
, the tight cluster temperature can range from 70F to 90-95 F.
Individual bees are cold blooded, but a healthy cluster of bees within a hive, with honey positioned correctly, has a great deal of control over its group temperature. As the outdoor temperature approaches about 55-57°F, depending on wind and sun conditions, bees within a hive begin to loosely centralize themselves near the bee nursery area (the brood nest) or near stored honey combs if the nursery has already been closed down for the season. As the day really cools to the 40s or so, bees will have clearly centralized themselves and will have begun to cozy-up. Colder still and the bees, just like our chilled, hypothetical human test population, will compact tightly. Some bees are in the interstices between combs while others are laying head first in empty cells. This tight configuration forms a solid, living cluster having roughly the volume of a soccer ball. The population at this point consists of adult worker bees, possibly some immature bees and the queen. No drones. They were all 'eliminated' during the Autumn and will be reproduced during the following Spring season. If baby bees are present, the nursery area will be kept at around 90-95°F while bees making up the outer layer will be nearer 40°F. If no developing bees are present, the center of the cluster will be around 70°F