The British Virgin Islands are some of the best sailing waters in the world, and the "when to go" question is mostly a sailing-and-hurricane question.
High season (December–April) is dry, breezy, and clear. Daytime temperatures sit around 27°C, the trade winds blow steadily out of the east, and the calmness of the Sir Francis Drake Channel makes for the easiest charter sailing on Earth. Christmas, New Year, and Easter weeks fill up months ahead and prices peak.
Shoulder (May–June and November) is the sweet spot. Sailing conditions are still excellent, hurricane risk is low, and prices drop substantially.
Wet/hurricane season (July–October) is the time to be cautious. The islands took a direct hit from Hurricane Irma in 2017 and rebuilt over several years. Charter companies typically operate June through October but with weather-watching protocols. September–early October is peak risk.
The BVI Spring Regatta in late March/early April is the regional sailing highlight. The Foxy's Old Year's Night party on Jost Van Dyke is the legendary New Year's Eve event.
Diving is good year-round; April–August offers the best visibility.