Some hogs, especially hoglets decide not to hibernate. If hogs are still around, it’s important to make sure they have food and water available. (I know some of you are already). Dry cat food is probably best in this weather, as wet cat/dog food would be likely to freeze. Water sometimes stays unfrozen if you put it in a wooden hog feeding box or put it in a sheltered place close to a house. But puttting more water out last thing at night at least gives the hogs a chance to access some before it freezes.
If hogs are still small at this time of year, they may need rescuing. 450g is the suggested weight. If you see any hogs looking on the small side it’s worth weighing them, contacting your local hog carer/rehabilitator and taking their advice.