Highly recommend a subscription to Crown Weather Service to follow activity in the Atlantic and Caribbean Sea.

While I can't disagree with maytrix's post about history in the months he mentions, its way more complicated than that.

The probability of a named tropical depression or Hurricane affecting the BVI sailing grounds in any given month is very difficult to predict.

Sure, the historical likelihood of a disruptive storm presenting itself in the months of July, August and September is higher than it is in December - June, history is a poor predictor of weather in this case. There are just too many variables. Most meteorologists and hurricane specialists have a hard time with historical models but do get a idea of a season's storm patterns that are informed by both history and pertinent weather factors that are present in the now and tend to shape the outlook for a given hurricane season.

The one smart piece of advise is to insure your July - September charter trip with a company that provides refunds of air, lodging and charter fees paid in advance in case of a named storm that precipitates an evacuation notification by government authority or a recommendation for an evacuation in the BVI.

That having been said, a tropical depression (not a Hurricane) is going to be disruptive in terms of wind and rain and un-fun conditions but it may not and probably will not cause the disruption of your entire trip. As a charterer though, you should know how to hunker down (tie up your boat) in a safe haven and if you don't ask for help from dock masters that do.

Your charter company may have something to say about where you can hunker down or if you have to return the boat to the charter base and this is assuming there is not a named storm that requires or recommends and evacuation. If this happens, you WILL get some kind of charter credit. Read your contracts.

You will get special instructions from your charter company about where to take the boat if there is a mandatory or recommended evacuation due to a named storm. If this happens during your charter, the company will likely relieve you of your contract, pick up the boat and move it to a specified safe spot themselves. This situation will very likely trigger a coordination of insured costs between your insurer and the charter company.