The hottest month in St Thomas is July when the average maximum temperature is 32°, average temperature is 29° and average minimum temperature is 26°.
The coolest month in St Thomas is January when the average maximum temperature is 28°, average temperature is 26° and average minimum temperature is 23°.
The longest days in St Thomas are in June, with an average of 13.2 hours of daylight per day. December has the shortest days with an average of 11 hours of daylight per day.
The sunniest days in St Thomas are in August which has the most hours of sunshine per day with an average of 9.8 hours of sunshine per day, making it a sunny month with few clouds. March has the least sunshine with an average of 4.5 hours of sunshine per day, making it a sunny month that is overcast at times.
The ultraviolet index is the highest in April when it reaches 13.5 and lowest in December when it reaches 7.5.
An ultraviolet index reading above 11 indicates an extreme risk of harm from unprotected sun exposure. Unprotected skin risks burning in less than 10 minutes. Take all precautions because unprotected skin and eyes can burn in minutes. Tanning will be safest before 10am and after 4pm but only with a good application of sun screen. For those with sensitive skin stay in the shade and wear protective clothing, a wide-brimmed hat, and UV-blocking sunglasses. Generously apply broad spectrum SPF 30+ sunscreen every 2 hours, even on cloudy days. Watch out for relections from water that may increase ultraviolet exposure.
The warmest sea water temperatures in St Thomas are found in September when they peak at 29° and lowest in March when they dip to 26°.
The sea is excellent for swimming all year round as the water temperature is very warm and ideal for relaxing and swimming for the whole day.
The wettest month in St Thomas is October with 19.7cm of rain and November has the most days of rain with 22.8 days with some rain, a very wet time to visit the beach.
The driest month in St Thomas is February with 4.5cm of rain and March has the fewest days of rain with 12.5 days with some rain, a slightly wet time to visit the beach.
The most humid month in St Thomas is September with a dew point (an indicator of humidity) of 25° which is very uncomfortable and fairly oppressive unless you are on a beach. At night you would most likely require airconditioning.
The least humid month in St Thomas is February with a dew point of 21° which is very humid and quite uncomfortable for most unless you are on a beach. At night you would most likely require a fan.
The most windy month in St Thomas is July when the average maximum windspeed is 32kmh and the average wind speed is 18kmh.
The least windy month in St Thomas is September when the average maximum windspeed is 27kmh and the average wind speed is 14kmh.