Well you are from NY & I am from CT so think of those days when it is nearly 100 & super humid..um..that black out a few years ago (luckily we had power!).
I look at it this way. When I am home & it is hot, if I am not in a pool or an a/c car/house, I don't go out.
But when I am in Disney, the weather is pretty much the same as it is here in CT when I don't want to go out for the oppressive heat (did I spell that correctly?).
So what we do (and we have been doing this since I was a kid) is go to the park for opening or just before & I do EMH's. Spend the am in the park & leave at around lunch time-either eat lunch at the park & leave or leave & have lunch at your resort.
Then go for a swim, cool off in your a/c room, take a shower & become refreshed.
Then go back to the park around 4 or 5 ish for dinner/rides/shows.
I am always amazed when we are leaving the park at around noon or before the oodles of day visitors coming in to enjoy that high noon sun.