High Heat Training
Decades ago, I used to live in a spot where for several months of the year many (even most) afternoon runs and rides would be done in temperatures from the high 80s to high 90s.
Basic rule of thumb, which I found to be particularly necessary with running but which also worked well for cycling: back off some, even quite a lot; ensure stellar hydration (before and during); and take as many brief rest brakes to refuel/refill as necessary. Only overheated once (on a run), where I didn't pay as much attention to the hydration component. Heat stroked, that day. Bad stuff. But, aside from that one incident, there was ~15yrs of cycling and hard distance running done in all weather, including over 100 occasionally. So long as the guidelines were followed, we ended up fine.