We went multiple years in late August and it was hot and sweaty but really doable, and the savings from free dining and cheaper airfare made it worth it. And then the last August trip we went on was just so much more awful, just much hotter than normal and I said never again. Well, we're going this year the first week of September because the cost savings were just too good. We plan to do what the others have recommended, be there at rope drop, spend the midday back at the hotel and then back to the parks in the evening. FWIW, with rain, we had two hurricane scares. One turned into a tropical storm when it hit, and the other was just really horrible rain. I think we still hit Hollywood Studios during the tropical storm and it was almost empty, and the other we stayed at the resort in the morning when the rain was really bad and went to a park when it lightened up a little. And there's usually a drenching thunderstorm in the afternoons in any case. Usually it just means leaving the pool or going inside for a bit. I do recommend constant hydration. Any snack/counter service will give you cups of water or ice for free. We have Camelbak bottles and will refill them throughout the day. Other icy drinks and cool snacks are good. We also carry little personal fans with us. We also try to alternate outdoor and indoor rides and attractions.