My eternal saying:
"The bastard sun is the real killer, not the hot air. If you can avoid direct sunlight (shade/head covering at day, or simply being out at night) you will be fine. Uncomfortable, but not super dangerous".
"The bastard sun" is a quote I took from someone in an another weather forum who lives in a hot climate and also worked in even hotter places. And I have been obsessed with it. I really hate the sun, and sunny summer skies in general. OK if it's cold I'll start acting like a Brit and start craving the sun.
I think even 70°F is exhausting for him.
For me 70-75°F DP is very nice. I like such moderately humid air. But 85°F DP is completely gross, and also exhausting (I have played soccer a couple of times in such weather). Unfortunately it's common here because of the very warm SSTs.