Given the choice, I would, without a doubt, go in October. Even though I've lived in the Midwest for years, I still do not like heat and humidity, and it definitely impacts my enjoyment of a vacation. For that reason, we avoid traveling to Disney during that May-Sept period. Hurricane season is officially June 1-Nov 30, but the most Atlantic hurricanes occur in Sept., followed by August, and then October. You would be decreasing the odds of encountering any problems by waiting until mid-October to go. And, as others have said, the other bonus of going during that time is that Food and Wine and the Halloween party are taking place! The best Disney vacation we ever had was when we went 6 years ago from Nov 6-14. It was cool in the evening, warm enough during the day to swim, the crowds were non-existent, and to top it off--the resorts were already decorated for Christmas and Mickey's Very Merry Christmas Party was going on! I would love to go again during that time, but am now reluctant to pull DS12 out of school. Good luck with your decision!