I hunt mostly in Kansas...I've always noticed the later in the season (ie hotter temps) that the turkeys are mostly active the first hour after flydown (visible feeding in fields) then after that they head back in to cover and prefer areas where there is shande and some water, like creeks. I like to hunt during this time of day the most so I really don't have to change my tactics. If you are hunting in the heat of the day get nearer their cover and water.
They can expose themselves again a couple of hours before flying up to roost as they travel back to roost sites depending on the terrain/location.
We had 92 degrees where I live yesterday so I'm sure I'll encounter this on my weekend hunt with the grandsons.