It is amazing what your body will adjust to. 100F all summer, and it's hitting 60-70F now, and I pull out the coats and crank on the heater. But, when we used to camp out in Florida in the summer, we would spend a couple of weeks without air conditioner living every minute on the beach, or riding bikes along the coast, and totally get used to it. You actually stop sweating as you acclimate to the heat. Then we'd go to get supplies at the local grocers and freeze our asses off in the air conditioner. I remember the my daughters lips turning blue and teeth chattering in 75F.
This is why I bawk at people shaming pet owners who leave dogs outside in the winter. If the dog is outside all the time, they get used to it. Just like we would if we stayed outside all the time. Humanity hasn't even had HVAC for 100 years yet... (maybe 70 years for the rich) and we survived, and so did the dogs. You actually risk your dog overheating by bringing them inside only on the coldest days.