We were there Nov. 9-16 (er, 17... add the extra day for flight delay), 2013. We experienced short rain showers many days. It was overcast or cloudy quite often too, but always very warm. Wouldn't have liked it for a beach vacation, but it was fine for diving. The bugs were quite bad, which often comes with rainy season. Used a lot of bug spray. We also found that some days the diving in the south was quite choppy for entries/exits, and the viz not so great.
We experienced that t-storm mentioned above on our last day. It was intense. The rains came down in buckets and flooded some of the condos in our complex. It was windy too. We had wanted to go to the park, but most of it was closed. The power went out for awhile. We were glad it was the last day, as it was pretty much a write off. Even when the torrential rain stopped, it rained off and on and the water looked churned up.
Thing is, hubby went in Nov. back in 2005. They had pretty much the same weather - often overcast/cloudy, some rain here and there... and also a big storm one day/night. They couldn't get to the park either.
So, although that is two great trips in Nov. despite rain, I think we will be looking for a different time of year next time. We're thinking of the spring - April/May?... or possibly later... Jan?
When is usually (I realize no guarantees ever, but there are seasons and patterns) the best time as far as the least rain... and wind... and calmest seas?