Though daily high and low temperatures don't change much throughout the year at the park, there is a rainy season, one that could include hurricanes.
The Tradewinds (the Easterlies) dominate the weather in the Virgin Islands, blowing east to west across the tropical Atlantic. The winter tends to bring stronger winds and less rain, and the summer tends to bring more rain and lighter winds.
In winter, cold fronts moving off the continent sometimes bring the Christmas winds down from the north. The fronts do not bring cold air as far south as the Virgin Islands, but they can create large waves breaking on the north shore beaches. Use extreme caution entering the water during such conditions, and heed posted warnings and advice from park staff.
In summer, tropical storms or hurricanes occasionally approach from the east and south. In 2017, two hurricanes tore through St. John and the rest of the Leeward Islands. You can read more about that by clicking here. More commonly, tropical waves bring clouds of African dust across the Virgin Islands.