I think they could. As a kid raised in South Dakota on a hog farm I saw it get mighty cold out there in the hog barns. We didn't heat them. I know some would hog pile together but it was still mighty cold. If a wild hog was close to the Minnesota/Iowa border it might make a big difference in temps for it.
I ain't never seen one but I have not been farther than 75 miles south of St Paul along the Mississippi. They're still dumfounded about cougar being found up in Northern MN. And now they have Cougar and Canadian Lynx mating and producing offspring. I can find and post the game trail camera picture "WildBill" took close to Duluth if you like.