The hottest I have ever felt it was when I was in Laughlin, Nevada and Bullhead city Arizona. It was 128 degrees and humidity around 60%. The construction job shut down at 11:30 in the morning. I consider that 5 weeks in hades..
Because of the effect on so many, unaccustomed to it and high humidity, drill was limited to right after breakfast, and in the evening.
One day we had been taken Mainside to the outdoor swimming pool for testing, and word was received after about 20 minutes to get us out of the water pronto.
The heat level with swimming exertion was the equivalent of 130 degrees, they said.
We were required to take handfuls of salt tablets throughout training. Believe the value of that helping has been questioned in recent years.