Please don't confuse the heat in Death Valley with humid heat. Don't get me wrong, that Death Valley heat will kill you, but as long as you have water and shade you will survive.
I posted about it before:
https://news.ycombinator.com/item?id=37455817#37459864
> You have to factor in humidity.
> Scottsdale airport currently (1:40PM) is 108F (42.222C) w/ 14% humidity, meaning a wet-bulb of 71.11F (21.72778C).
> London tomorrow at noon is 86F (30C) w/ 52% humidity, meaning a wet-bulb of 72.76F (22.6444C).
> London will actually feel nastier.