O.K., I can confirm with 100% certainty why the random joggers keep freezing. Every time I find a dying jogger, they're still in their workout clothes, but they're doing something other than jogging, like talking to another sim or sitting on a bench or waiting on line at a snack kiosk. So, the joggers are dying because they stop jogging, the anti-freeze buff wears off, they don't automatically change to their cold weather clothes after they've stopped jogging, and they freeze to death from that.
Yeah...The devs need to fix that little hiccup...
The only good thing that's come of it is that in one of my saves, Mortimer Goth froze to death and MCCC hooked Bella up with Caleb Vatore. O.K., go girl...