Hi there,
I wouldnt stress about it too much. We are getting married August 21st, so I know how you feel about the rain, crowds, and hurricane worries. But, you can't worry about details you can't control. I mean, if the heat truly bothers you, then I would think about changing your month. My fiance and I were there this past August for an 8 day vacation (and to book our wedding in person!) and it was HOT! I mean, really hot.

But, on the other hand, its summer and your in Disney. Everything we are doing with our wedding in going to be in the AC and since I am a teacher,

I was limited as to what months I could get married. We choose the end of August and the crowds weren't bad at all. I mean 20 minute lines or so, sometimes longer, but it was worth it. We found ways to keep cool.

Also, in the 8 days we were there, we didnt have a single day of rain. It was weird. One quick 10 minute shower and that was it. So here is my advise: If you HATE the heat and cant stand the thought of sweating, then I would change the month. But if your like me and the heat doesnt get to you that bad, then I would stick to your date. You can't prevent hurricanes and you can't predict the weather. (Watch, Ill have the worst hurricane
ever the day of my wedding! Thats my luck! hahahaha). But, regardless, I wouldn't worry about things you can't control. If you like the idea of August and it works for everyone attending, then stick with it and just wish and pray that it stays dry.

Thats what I'm doing! Good luck with your planning!