Last fall as you were buttoning up your bees for winter, you most likely took measures to ensure that they were well fed and protected from excessive moisture. Those measures will be paying off now as your bees are preparing for the coming of Spring. With January being unseasonably wet and warm, your bees have been more active and thus burned more calories. That translates to a less efficient use of food stores.
If they're alive now, they have most likely staved off the threat that Varroa poses. Most colonies die out in November or December if they have succumbed to Varroa. Good job!!!!
Take a peak when you can. Look for signs of life. If your bees are at the top of the hive, they have migrated through or past their honey stores. Typically the cluster will not move back down. This puts them at risk of starvation.
Now is the time to ensure that there is some form of supplementary feed such as a candy board, pollen patty or dry sugar pile for them. Be sure to monitor your supplementary feed throughout the rest of Winter and into early Spring. If your bees consume what you've provided but still have weeks left before they can forage nectar and pollen, they could possibly starve to death.
If you installed quilt boards, check on them to ensure that they are still dry. If not, change out your wood shavings or leaves etc, with fresh, dry insulation.
We're heading into our last stage of winter! Let's finish strong and come through the off season with bustling hives ready to build up strong in the spring!