I have been to Disney every month but March. For a 7-10 day vacation, the end of August is my favorite. And I hate the heat. With the exception of AK, the parks have plenty of air conditioning. Crowds are really low. The evening extra magic hours are not overly crowded. We are NOT morning people, but did fine with the heat. However, we were AP holders, so we could park hop, and that seemed to help. That also gave us the ability to go to AK on the coolest predicted day. One thing that you can count on (no matter the time of year because we had it happen right before Christmas last year) is that the parks will be EMPTY after a rainstorm. Walk-on empty. We are water drinkers by nature, so we would get the ice water from CS places. If at all possible, wear quick dry clothes. Especially shorts and unders.