The hottest month in Costa Rica is April when the average maximum temperature is 34°, average temperature is 28° and average minimum temperature is 23°.
The coolest month in Costa Rica is December when the average maximum temperature is 31°, average temperature is 26° and average minimum temperature is 22°.
The longest days in Costa Rica are in June, with an average of 12.7 hours of daylight per day. December has the shortest days with an average of 11.5 hours of daylight per day.
The sunniest days in Costa Rica are in February which has the most hours of sunshine per day with an average of 7.8 hours of sunshine per day, making it a quite sunny month with some cloud cover. October has the least sunshine with an average of 4.7 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 15.1 and lowest in December when it reaches 10.7.
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 Costa Rica are found in April when they peak at 29° and lowest in September when they dip to 24°.
The sea is best for swimming between December and August when the temperature is above 27° which is very warm and ideal for relaxing and swimming for the whole day.
The wettest month in Costa Rica is October with 21.5cm of rain and the most days of rain with 18.5 days with some rain, a wet time to visit the beach.
The driest month in Costa Rica is February with 1cm of rain and the least days of rain with 2.3 days with some rain, a very dry time to visit the beach.
The most humid month in Costa Rica is June 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 Costa Rica is February with a dew point of 20° which is somewhat uncomfortable for most people in cities but fine on a beach.
The most windy month in Costa Rica is February when the average maximum windspeed is 31kmh and the average wind speed is 17kmh.
The least windy month in Costa Rica is October when the average maximum windspeed is 17kmh and the average wind speed is 7kmh.