Try to avoid Orlando in July and August. Hot and humid and a horrible place to be when walking round theme parks (if that is what you are doing).
We went in February a few years ago and spent the whole two weeks in t shirts and shorts, right up to 9pm.
One web site says:
"Unless high humidity, afternoon thunderstorms, and masses of hot and sweaty tourists sound like your ideal vacation, then avoid Orlando in the summer months (June to August)"
http://www.tripadviso...r.And.When.To.Go.html
A person on another forum says
"We travelled to Orlando in August 2010 and it was VERY hot.It was mostly humid which I found to be very uncomfortable. I came home after 10 days with no tan as I just could not sit out in it. Having said that, we only had 1 heavy shower in the 10 days that we were there. Have booked to go back again as it is an amazing place but we shall be travelling in April as I think it is cooler. Have a great time if you go.:)