We often book in Sept simply because it is much cheaper and also because we are not the type that can't deal with changing ports at the last minute. We look at it as an adventure. As said, hurricane 'season' runs from June 1st to Nov 31st with the most active time in September. Understand that there has been a hurricane in every single month of the year at one time or another! <G> Outside of those five months though it is exceptionally rare. If you are up for a gamble, (make sure you do take cruise insurance just in case the port is wiped out), then cruising in Sept can be great and very affordable.