As winter approaches, the population of the hive decreases and all the boys (drones) are kicked out, as they are useless this time of year. The only time they are really needed is in the spring and summer when a queen needs mated, otherwise they perform absolutely no duties around the hive.
As the temperatures drop, the bees form a cluster around the queen and buzz their wings to generate heat and keep her warm. The temperature in the hive will stay 92 degrees, no matter how cold it gets outside. The cluster will migrate around the inside of the hive to reach the stores of honey, which they eat to survive.
It is not advised to open the hive until the temperatures get above 55 degrees in the spring, although some beekeepers take a quick peek to look for low honey stores, which could require emergency feeding. Many colonies die of starvation in winter and especially early spring, before flower plants give them a food source again.