I live in the tropics, just a few degrees of the equator, daytime temp. up to 35C in the shade, and 95% humidity.. here we ride early, or cover arms and legs to avoid the directly overhead sun.

Plenty of water and stops to cool down.. (at least for me.. the young uns just carry on..), shady true lined route are also preferred. But in the end its just hot... to an extent you get a little used to it, but here its all year so we have no autumn to look forward to..but no winter either...