I live in Tortola, year around, with my Leopard 45 catamaran
in the water, and spend some time every day keeping up with the tropical weather developments. About once a year we have to do some rudimentary preparations for an impending storm; you have to start early, because it can quickly become "too late" if the storm materializes. Every few years we have to do a full-on prep. And, about every five - eight years, we actually get hit. And, mid-August to mid- October are the most likely times.
What happens is that you are unlikely to get hit by a storm, but the chances of having to cut your vacation
short because the boat needs to be prepped (just in case) are a bit higher. If your vacation is not thus impeded, you will have lots of good weather, but most likely one tropical wave will pass through and you may get some rainy and squally weather at some point. Also some wind, and some calm. It's pretty enjoyable, actually, particularly if you don't depend upon lots of land and bar activity, because many will be closed. And you definitely need to buy decent trip insurance.
What I do in the BVI is run captain
only and fully crewed (with chef) charters on my boat. And I and many others, for instance, will not do a charter during that time of the year unless the guests have bought the insurance. And, yes, on one occasion it had to be invoked, due to cutting a trip short for storm prep. The guests got paid in about three weeks, no problem.
But, if you understand all of that, it's still a good time to come. And, if you have any interest in a captain
(definitely NOT a bareboat) that is very well equipped and in great condition (much better than a bareboat), and that goes out for a very reasonable rate, PM me, or go to a reputable broker and ask for Jet Stream.
Best of luck,