Yes, it's a problem in winter. Some people use these discs that heat up in a microwave. You can put the bowl of wet food on top of them.
I would try to find a sunny spot against a wall. That helps a lot, but not on a cloudy day. It's a good place for a water dish too.
Plastic will not freeze water as fast as a metal bowl. Some people use those thick rubberized bowls that they sell at feed stores.
In the coldest temperatures, I just fed dry food to my colony. I did the best I could to give them water, but sometimes it was so cold - zero to 5 degrees - that water froze as I poured it out of the bottle.