[throwaway72762]

Yes, this is exactly right. The wet bulb temperature in parts of Texas and Florida in the heat wave a week or two ago got close to the limit of human survivability. Five years from now Texas, Florida, the Persian Gulf, and South Asia are all going to be seeing that limit exceeded at least briefly every summer.

[bscphil]

I was in New Mexico a while back, and being outside walking around in 35 C heat was completely comfortable because of how dry it was. Relative humidity less than 20%. It's so dry that the heat index (by the National Weather Service's formula) is actually less than the true temperature.

By comparison, life at 60% humidity in the Northeast at 30 C is considerably more miserable without air conditioning. Without a fan blowing in my face constantly to improve evaporation, my head starts to feel like mush after about an hour.

Conversions: 35 C = 95 F, 30 C = 86 F

[throwaway72762]

Definitely. The only place in the deserts in the US that will be an exception to this is Yuma AZ because it is close to the warm ocean waters to the south of it so it's more humid. But it doesn't have a huge population unlike Houston or Miami.