Plan any planting and tidy up the apiary
Decide what you are going to plant/sow/grow for your bees this year. Clear vegetation away from the front of the hives. A bright tile below the entrance ensures it stays clear and allows you to see the corpses; more than 100 deserves investigation.
While winter bees often live 150 days or more, by now many will be dying. Early in the month, check hive entrances for dead bees choking them. Turn entrance blocks upside-down as it helps the living ones get out.
A swift first inspection
Only disturb the brood if it really is mild, 15°C, better to do this in early April. Swiftly check that the colony is building up as it should be; four good seams of bees is fine and, importantly, that they have enough food. As brood rearing will really be starting, more colonies starve at this time of year than at any other. If necessary, feed a medium strength syrup (1 kg: 1 litre); they should take it from a rapid feeder if you have good insulation above.
If there are no bees to be seen when the crown-board is lifted, start worrying. If your bees are dead, clear up everything straight away or close the hive until you can. This prevents robbing and/or disease transfer to other colonies. The commonest cause of loss over winter is starvation. While even a well provisioned colony can become isolated from its stores, if there are now no stores and the bees are head down in the cells, it means that you did not feed them well enough last August/September.
There may or may not be a heap of dead bees and/or plenty of stores. If the cause is not obvious, it might be virus vectored by Varroa. Did you treat for Varroa last summer? Faeces may also be seen inside. If in doubt, destroy the frames. Woodwork scorched with a blow-torch can be re-used with new frames and foundation.
At your first inspection, check queens are not drone-layers. If one is, she did not mate properly so has run out of sperm. If you think the colony is otherwise healthy, catch and kill her, move them next to another colony and unite.
Check Varroa levels and signs of disease
On a better day, put an upturned roof on the ground, lift the brood chamber on to it and scrape any dead bees off the floor. After reassembly, insert Varroa trays and monitor mite fall over four days; there should be no more than eight or nine per day. Look for streaks of bee faeces around entrances. If there are any, the bees may be suffering from dysentery or Nosema. Clean comb helps. Prepare frames for the season ahead. Add foundation to the frames you have made up.