Depending on the severity of the weather, the Captain does makes decision on alterating the itinerary. For instance, When i took the 7 Day Eastern carrib. Cruise back in Oct '01 , there was a hurricane going on near St. Maartin, which was one of the ports to stop at, but it was rumored that the hurricane was going to come up and hit the Bahamas area few days later. The Captain made a decision to go to CC first, instead of the last day, which is was a beautiful day and we also ended up in Puerto Rico instead of St. Maartin which was great also. Later on that week, the hurricane never did hit Bahamas, (went down further instead of up) the Captain allowed us to go back to CC again!!! We had the best time considering we went to PR and then CC twice!!!