I have some difficulties with heat. Fortunately, I live in New England and not in a southern state!
I have been riding on the warmer days (90's F) in the evening. It really helps that it is still light out at 8:30 PM or so!
I am anxiously awaiting the Fall weather... nice bike rides while taking in the Fall Foliage! Bicycling and Fall foliage... it's "double the pleasure, double the fun!" (In my own opinion!)
Hopefully, by then, I will have increased my skills and my stamina, as well!
~Wishing you inner peace and abundant joy~