I suspect some of the hogs are finding the ‘strange’ weather a bit confusing! But hibernation isn’t solely linked to temperature, so it’s quite possible the hogs have gone to hibernate. Hogs do tend to go in and out of hibernation a bit, even in ‘normal’ weather, so some people always leave a certain amount of food available, in case. It’s important to always leave water available all day every day, including during winter, in case a thirsty hog should happen along.
Hopefully the hogs will be back after hibernation, if not before then.