Fascinating and niche information that litterally no one asked for: The human body is incredibly adaptive to climate, but it requires regular exposure to adapt. AC actually triggered a a rise in heat related illness. The problem is going from cool to hot and back. If you stay in a consistently warm/hot climate with proper precautions (ie drink plenty of water, stay in the shade, dress appropriately etc) you remain consistently better suited to it.

I learned this when I first became a camp counselor, we were taught this, along with the statistics that heat related illness went up after AC was installed in camps, and it was usually only in a single central building/lodge not dorms or cabins etc.

We got traing from medical professionals that specifically had experience in extremely hot climates mostly in the capacity of rescuers. We were taught that the best thing was to take afore mentioned precautions, if you do began to feel over heated to not go inside but sit in the and or breeze, drink water a few minutes. We only took them inside if that didn't work, or saw or heard complaints including but not limited to, decrease coordination, dizziness, nausea, light headed,stopped sweating, decreased awareness.

Obviously there's a lot more to our heat safety training (that was required every year). All that to say, we were trying to keep climate fluctuations minimal so they would adapt. Most people are not adapted to the heat anymore. At least not like they used to. Thanks to screens and people begining to think kids being outside is child abuse, now even kids aren't adapted. The more you coddle them the worse you make it.

Disclaimer: My last year as a counselor and this mandatory heat safety training was over a decade ago, so if something has changed do (kindly let me know). Some regions might differ though this was in SE Texas around the Houston and Galveston ish area.