There's also such a thing as acclimatization. https://en.wikipedia.org/wiki/Cold_and_heat_adaptations_in_humans https://en.wikipedia.org/wiki/Cold_and_heat_ada

There's also such a thing as acclimatization. https://en.wikipedia.org/wiki/Cold_and_heat_adaptations_in_humans https://en.wikipedia.org/wiki/Cold_and_heat_adaptations_in_h... If you're living in a hot area but used to AC, you're far less able to cope with loss of AC than someone who's been living without it the whole time. Further, modern dwellings are build with AC in mind. Older ones—by which I mean 50+ years ago, let alone dwellings the native people of the area lived in—were built with airflow & cooling in mind. They might be situated to take advantage of local conditions like shade or prevailing wind. Building for AC means some of that's less important, so gets ignored, and other aspects are deliberately broken to improve AC efficiency (window sizes shrink and there are fewer of them, maybe with none at all on some entire exterior walls, open paths to attic areas that allow up-and-out airflow are avoided, et c). Modern houses become traps in extreme heat if the AC is off, not shelters.