I'm in central Florida and it has been hotter and more humid earlier this season than last. During the week I just get out whenever I can but now take along extra water and electrolytes even for a 2-hr ride. For me, 0830 is way too late for a century or longer; I would need to be rolling by 0600-0630.
I did 75 miles the 2 weeks ago and this is what I brought/did:
_2 large water bottles: one insulate with icy water, the other frozen with electrolyte mix
_bag of fig bars and peanut butter pretzels
_left early-ish (0715)
_started slowly and tapered off
_started pushing something salty an hour in
_stopped for ice about every 2 hours
_took a 15-minute shade break in the final third of the ride.
I was able to finish strong and feel good about the ride.
Heat is nothing to play with, but starting early and managing both nutrition and effort should get you that 109.