I worked in un-airconditioned machine shops and un-airconditioned power plants all my life where working temps could exceed 140 degrees which is medium rare for a steak.
Power plant only allowed 20 minutes at a time in the area with a one hour period to hydrate and cool down. 100 degrees in the sun felt cool.
Summers in Oklahoma didn't bother me much but since retiring I'm not acclimated to the high heat and its no longer bearable.
Might have to turn into a snow bird in the RV?