You'll be fine....we go every August and it's just brutal but as I've mentioned before, as long as I'm at Disney, it could be 100 degrees every day! My son and I spent two summers in Houston, TX in July [for a baseball camp] and I actually think it was hotter there. 105 degrees plus 1000% humidity made for some really gross days.
I live in Connecticut and tomorrow is expected to be one of the hottest days of the summer! Go figure! I'm a physical education teacher so it stinks for me but yea, HOT everywhere it seems. We'll be complaining of cold real soon. I'm sick of winters.