Tuesday, December 22nd, is the winter solstice. That's when the sun reaches its farthest point south and day light is at its shortest. From now on the days will be lengthening. Lengthening days are commonly thought to trigger the hive to begin raising brood again. Brood raising is initially very slow due to the limited space (warm area) within the cluster where the temperature is warm enough (92F) to allow the eggs to hatch and larvae develop.
Since the bees are already beginning to think spring, you, the beekeeper, should also begin thinking about your beekeeping plans for next spring. Now is the time to order and assemble any new equipment. If you plan to improve you apiary genetics by ordering new queens, remember that queen suppliers usually begin taking orders for spring and summer queens beginning January 1st.