I grew up in AL, which is hotter and more humid than TN ( I have spent time there also.) When I was young, I did landscaping work in 100 plus degree heat, 90 plus percent humidity, 12 hours per day. In the dog days of summer those conditions can persist for 30 - 40 days without abatement. I have been in Tucson over 20 years now. In AL, you do drip with sweat as soon as you are out of the shower, and worse outside. The heat and insects are so miserable, most only recreate around water in the summer. When you stop sweating and skin gets clammy, you know you are in trouble and need help immediately. The big difference is out west, you are sweating more but not getting wet because it evaporates so quickly. You never get that warning that you are really in trouble. You slip into a cognitively demented state due to dehydration before you realize it. It can happen in just a few hours.
Thank goodness for Liquid IV. You should never go out without it here. Last week a relative woke up to a flat tire and texted for help early in AM, but it was already over 100 degrees. I woke up and went without hydrating or eating. BIG MISTAKE! I changed the tire, put the old tire and floor jack back in the vehicle, and nearly passed out. They went inside to get me a Liquid IV and before they came back I was sitting on the ground, back against the bumper, knees up, and head between them (I had to sit down before I fell down). It was difficult just to keep my knees up, but if I put them down, I would start to pass out. I never felt too hot or unwell until I started to get dizzy. After drinking about 40 or 50 oz's of water with Liquid IV in it, and eating a small snack, in about 20 min. I was able to stand up and drive myself home, but I was pretty well worthless the rest of the day.
We lost another poor hiker this week. Local guy, late 20's, extremely trim and fit, went on a solo hike on the edge of town and never made it back to car. I have hiked solo on that trail many times, but not in 110 degree heat. Sherrif Dept. found his car at the trailhead same day (late) and started helicopter and on foot search. Did not find him before dark. helicopter found him dead off trail the next day. Probably got confused due to dehydration and wandered off trail for a while until he sat down, passed out, and didn't wake up. He was young, trim, fit, and an experienced hiker and got in trouble so fast he could not save himself. Tragic.