The actual hurricane season is far shorter than the "insurance hurricane season". This is all about statistics and probability, so it is always a question of risk. Frequency of hurricanes follows a standard bell curve:


You can see that the frequency for July remains very low. In addition, modern weather forecasting systems and models have gotten a lot more reliable and semi-accurate storm paths can be calculated many days out. Taking all these factors into account, I'd charter in the BVI in July. I'd be cognizant of the weather and the charter base will have a plan to get you (well, the boat) back into base if the weather looks iffy.