Im sorry but to the op, have you ever been to WDW any other time? I mean yea, the heat, but I guess since Im from the south as well Im kinda used to it and come to expect it when I go to FLA. Ive been in the winter and spring and it is nice when its cooler. But this past trip I had was the first time Ive been to WDW in september and during the "off season" It was hot, but nowhere near as bad as July, and the crowds were practically none existant again compared to July. I was amazed, I walked right on almost everything. I even got to see the second night of joy and see Mary- Mary and Smokie Norful(A very very good treat, because we didnt know or plan our trip around it and found out at check in, and went to the MK and found someone and bought the wristbands.) And now that Im able, I should be able to vacation to WDW more during a non peak time, so I plan on going every chance I get when there are hardly any crowds.
And I also didnt see but like 3 tour groups in all of WDW this past trip. Compared to the like the 500 or so you see down there in July. So it was really great. I will def. try to go back down there again during this time of year.
I've actually been to DW more than 20 times, granted most of those trips were in the cooler seasons, January, mid April, mid November October, December, but I've also been in September, late May and June as well. I also seriously doubt that the weather in July was much worse than the weather we experienced. The temperature ranged from 90-96 every day we were there with high humidity. July is about the same, it doesn't get that much hotter in fact Sept avg wise is only 1 degree cooler than July and is a degree higher humidity wise than July.
I do strongly agree that non-peak times are the best time to go especially for the manageable lines, but September while slower is not the ideal time in my opinion to go, the quick rush from place to place seeking AC takes away from the overall experience. I'd much rather take my time during other slower periods such as mid November or early December when the crowds are still relatively light and the weather is much more pleasant and far less rainy.