I just saved one sim from Grim after she collapsed from freezing. She was on the street in front of my sim's house and my sim convinced her to group up. It would take too long to walk back to my sim...
My teen Sim doesn't change into cold weather clothes when taking the bus, and because of the bug I have where Sims disappear then reappear without actually going to school or work, she's almost frozen to death a couple times too.
Probably going to turn off effects from now on too...