As far as RCCL, they have a meteorologist on staff, James Van Fleet, to give them as accurate information as quickly as possible. Odds of any cruise cancelling are slim,
just don't fall in love with any port you are scheduled to visit this time of year. The captain is literally in the same boat as you, he will decide what is and isn't safe and that will be the final say. You may get some advanced notice like the
DCL Fantasy and RCCL Allure did this past week, or it might be a day-of decision. Hard to say.
Enjoy your cruise and I hope it is uneventful as far as weather is concerned!