I don't think they are much bothered by cold. I've seen a huge flock of wild ones sleep in the bare trees on the hill behind my pasture, in minus 14. I lock all my birds into "Fort Apache" at night for safety from predators, but also so their body heat helps keep the coop buildings above freezing and their water dispensers stay ice-free. The ducks, especially, would never go in if I didn't herd them.
If you have the commercial turkeys, and you've been reading over the posts about them here, you've probably seen all the downsides to that type of turkey outside the poultry industry. Have you thought about starting over with a breed more backyard-friendly? You could probably keep your hens until they started having health problems, but if you have a 50 lb. aggressive tom, eventually he is going to do you significant harm. When I had sheep, the young rams sorted themselves out into future fathers and Lambchop by their temperament as they hit adolescence. Of course, a turkey can't kill you like a ram can, but still, being attacked all the time isn't fun, especially if he gets you in the face.