I'm never ever, Never Ever, NEVER EVER...

[RainK]

We have been in May, Late Aug, Sept and Oct before and anything over 85 degrees is hot...hot is hot, so its all realative in our book.
We are from MA and are used to humidity, so although we do complain, we have no problem heading back to the resort for a couple hours to swim.

We went 3rd week in Aug last time and are heading there at that time again this year. The crowds were manageable and less crowded than they were in late May when we went.

As far as rain, in Aug, it only really rained 1 evening but we bought ponchos and had an absolute blast in the park! Not to mention, it was practically empty due to the rain. We loved going late August.

 

[FigmentFan1975]

We've been 3 times in August for a week, with young children (ages 6 & 8) last time in '09. We've never taken a midday break or felt the need to. We hit parks at rope drop and stay until 9/10pm most nights, with a few earlier days.
Always just take a nice lunch and dinner break (CS) in the A/C, relax and are fine in the heat. Hit some indoor attractions/shows in the afternoon to relax, a water ride, or shop in air condition... Most parks, except AK, there is plenty of A/C to keep cool in. Have fun!

 

[rapunzels]

I can tell you that without any amount of uncertainty that we will never come back in June.

Ditto. Just got back last night and I was glad to get home. The parks were slammed this last week and it was hot/humid the whole week too. Both are not a good combo. We went the 3rd week of June last year, and I do not remember it being like this.. We may have took more mid day breaks last year.... all I know is it was a rough week.