I went on a Western Caribbean cruise in September of '95 and an Eastern Caribbean cruise in September of last year and had no problems with either. I think it's really a roll of the dice. We're doing East & West Caribbean next month - we'll see how it goes. I have read that someone on an 8/18 cruise to the West Caribbean had to change to East, and still ran into weather trouble and had to skip a couple of ports. Truly hard to tell what Mother Nature has in store at any point it time.
From Seattle, where the weather changes every hour or so, but luckily only 1 hurricane in the last 7 years!