I live in the South where temps are now in the 90s during the day. I just don't ride when it's that hot. I wait until evening or simply do not ride. If there is a ride in the heat of the afternoon, I just don't go. Or I will ride in the mornings on weekends.
With the mention of golf above. I have been on MANY golf forums where the "purists" get on to people for riding in golf carts. I ALWAYS make a mention to them that you just can't do that in the South. With temps in the 90s and 100s you simply can not walk a golf course and be safe. Sometimes you just have to use common sense. That isn't a put down, it's just good advice

You ride for enjoyment and exercise and.............TO BE HEALTHY. Well, there is nothing healthy about heat stroke. Be safe. 50 miles on a bike is a long ways, whether or not you may think it is. It IS!