I always wait until 6-6:30 to ride in the summer. (and usually put my horse up at dark.) If it's so hot that I can barely stand to be outside, then I'm not going to ride, and if I do, it would be bareback and involve water, lol. After our workout (arena work), I always take my boy on a trail to cool off and then I untack, spray him down with the hose, feed, and then turn him back out with his buddies.