You'd be surprised how much it does not. Not saying its the same amount of folks out during Fall/Winter/Spring, but a surprising amount due walk.

I think people tend to do those activities in the early mornings or after the sun is down.

Proper hydration habits and efforts to acclimate help greatly with this.

Frequently 120+.

If by "frequently" you mean "that one day in 1990"... The single highest day of the year for most years is 115 ± 3.