The hottest month in Saint Barthelemy is September when the average maximum temperature is 31°, average temperature is 29° and average minimum temperature is 27°.
The coolest month in Saint Barthelemy is February when the average maximum temperature is 28°, average temperature is 26° and average minimum temperature is 23°.
The longest days in Saint Barthelemy are in June, with an average of 13.2 hours of daylight per day. December has the shortest days with an average of 11.1 hours of daylight per day.
The sunniest days in Saint Barthelemy are in August which has the most hours of sunshine per day with an average of 10.2 hours of sunshine per day, making it a very sunny and pleasant month with long bright days. March has the least sunshine with an average of 5.1 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 13.6 and lowest in December when it reaches 7.6.
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 Saint Barthelemy are found in September when they peak at 28° 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 Saint Barthelemy is May with 10.3cm of rain and December has the most days of rain with 20.1 days with some rain, a very wet time to visit the beach.
The driest month in Saint Barthelemy is March with 0.3cm of rain and April 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 Saint Barthelemy is September with a dew point (an indicator of humidity) of 24° 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 Saint Barthelemy is March with a dew point of 21° which is somewhat uncomfortable for most people in cities but fine on a beach.
The most windy month in Saint Barthelemy is July when the average maximum windspeed is 30kmh and the average wind speed is 18kmh.
The least windy month in Saint Barthelemy is September when the average maximum windspeed is 22kmh and the average wind speed is 13kmh.