Chickens in cold weather

I'm writing this as someone who believes farm animals should be treated well and fed a proper diet. For chickens, that includes not jamming them into cages or packing them so tightly they have no room to turn around or wander, and should have time to be out, pecking around, and doing what chickens do. But I've got a question: In the winter, how much cold can chickens tolerate? I'm thinking that in colder climates, chickens are gonna want to congregate indoors all the time and huddle together for warmth anyway. If that's so, then chickens whose lives occur during the winter months, of their own accord, aren't really going to be free-range or pasture-raised anyway, right? I'm not making an argument or taking a position with this question, I'm looking for information that will help me understand what actually happens.