Ideas
Sims keep dying at my getaway, specifically from overheating. They are dying inside with the air conditioning on, in their hot weather clothes, and when it is cool weather outside. I've restarted my game, restarted getaways, and I don't have any mods. I've had about 20 sims die in this exact scenario. I've tried everything to make it stop.
I'm having the same issue, it's like the world is all mixed up with the temperatures. I was testing some stuff and held a romantic getaway in the DEAD OF WINTER, and everything was fine, even though sims did stupid stuff like going swimming in the open water when it was freezing out. Then I did it again in the spring, and they started freezing to death left and right, even though it was just either warm or cool, they were changing into cold weather outfits, standing around the bonfire, were inside, warmed up at the fireplace, etc.
edit - I continued playing after disabling weather effects (and fist-bumping Grim a whole lot) Yeah I think there is a kind of mismatch between the weather/temperature the Sims are experiencing, and the weather we see? I am getting dialogue prompts to talk about the cloudy weather on what it says is a sunny day, and the sky is clear. every other time i get complaints about the weather as a dialogue option, it matches the weather it is currently. It did become cloudy later.
Though this does not explain why they are dying after they have moved indoors and have warmed themselves by a fireplace.