As the old saying goes, it ain't the heat, it's the &*^%$!! humidity. When I lived in S. Colorado, I was personally hurt and offended when the high for the day this time of year was below 100F. But there was effectively no humidity, and things cooled off nicely at night. And yes, I was active. Here in the Midwest, I wilt at about 85, and things just stay hot (and humid).

I'm wilting now.

FWIW, I just ran into an old email from DH that he sent sometime this last spring "It's 40 degrees out, I hope you're on your bike." (I think I was...)