St. Thomas and Charlotte Amalie have a classic Caribbean climate — warm year-round, with a wetter season from June to November and a drier, cooler season from December to April. The dry season is peak tourist season, coinciding with North American winter escapes and the busiest cruise ship traffic.
December to April brings the best weather: temperatures in the mid-to-upper 20s Celsius, low humidity, and clear skies. This is also when hotels are most expensive and the town most crowded with cruise passengers.
May to November is quieter and cheaper. Temperatures are similar but humidity is higher and afternoon showers are common. The official hurricane season runs from June to November, with peak risk in August and September. Hurricanes are not a daily event, but the risk is real and travel insurance is advisable.
The best compromise for many travellers is May or early December: crowd levels are moderate, prices are lower than peak season, and the weather is usually excellent. The cruise ship calendar drives much of the day-to-day variation — a day with five ships in port is fundamentally different from a day with none.