I live in the Phoenix area. Summer heat here is akin to cabin fever in Alaska. (I’ve lived in both)
Literally coooped up in air conditioning and not able to enjoy the outdoors. I’ve also observed that people from Northern countries do not tolerate the heat as well. Although it always amazes me the amount of fair skinned redheads around this area. I do think you have a point with your tolerance to heat. I do think we adapt however. I used to not sleep above 68 degrees and now I can tolerate sleeping at 74 degrees. Still grateful when summer is over.
Seems as though I put on weight in both seasons however. Yikes!