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...
I noticed that your sims can't jog during a blizzard. Using Dr. June's weather machine, you can set the winter forecast to snowy. Doing so can create a ongoing blizzard. Could help save some sims! :)
...Or maybe not. Marcus Flex just went out in a blizzard wearing his athletic wear anyway. :|