I have seen this issue as well, but I also see it when I go to the gym in the winter. All the NPCs and some of my other played households show up dressed in their athletic clothing. Promptly, they freeze to death because they won't go into the gym. It kills both NPCs and previously played households (of which are approx five households totaling 12-ish sim). I then end up with several tombstones sitting outside the gym because everyone stops to watch/cry the dying sim.
As a result, I have had to stop visiting the gym lots in the winter. This happens at all gym lots from each expansion pack (all).
