My main sim is a vampire, so I'm always having to manually change his hot/cold weather outfits anyway. Temperature extremes can't kill him of course, but my vampire still likes to feel comfortable (poor baby is always room temperature since he's well...dead) and wouldn't live anywhere without a thermostat. :D I tend to be ridiculously particular in CAS and like to make sure I have both indoor and outdoor outfits for hot/cold weather to suit different temperatures/seasons. I change them manually as appropriate.