My advice is to take historical weather patterns into consideration, but don't let them alter your plans too much. Averages are just that , there are still extremes on both ends. I remember I was at WDW the week between Christmas and NY in the early 90's and it was HOT everyday. Even the locals were saying that the heatwave was very unusual. I was there more recently for 2 weeks in May 2000 and then another 2 weeks in September 2001. Out of those 4 weeks, we had exactly 3 hours of rain TOTAL! Obviously, we were lucky, but my point is you never know.
This year we are going for 2 weeks in August and family members are concerned about the heat. Well last year we went to the White Mountains in August to escape the heat and we hit 100 degrees on 2 days - the rest were well into the 90's. I read posts on this board that people went in August last year and stated that it was hotter back home in the Northeast than it was in Florida when they were there. You never know!
My advice - you can plan around the crowds but there is little that you can do about the weather. Just go, have fun, and deal with whatever Mother Nature throws at you.
