Sorry it took a while, but here is your answer from one who has cruised this ship many times. We've found September to be a great time to take this cruise, weather-wise and otherwise. The hot and rainy season in Polynesia is December through March, so you will be missing that. You will also be missing the peak Northern Hemisphere summer season, so the ship may be a bit less full than during our summers. Service is always great on this ship, but it is even better when it is not totally full.