Annual average weather for Ko Samui, Thailand

Annual Temperature for Ko Samui

The hottest month in Ko Samui is May when the average maximum temperature is 33°, average temperature is 30° and average minimum temperature is 27°.

The coolest month in Ko Samui is January when the average maximum temperature is 30°, average temperature is 28° and average minimum temperature is 25°.

Annual Sunshine for Ko Samui

The longest days in Ko Samui are in June, with an average of 12.7 hours of daylight per day. January has the shortest days with an average of 11.6 hours of daylight per day.

The sunniest days in Ko Samui are in July which has the most hours of sunshine per day with an average of 7.2 hours of sunshine per day, making it a quite sunny month with some cloud cover. January has the least sunshine with an average of 5 hours of sunshine per day, making it a sunny month that is overcast at times.

The ultraviolet index is the highest in March when it reaches 14.8 and lowest in December when it reaches 10.5.

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.

Annual Sea Temperature for Ko Samui

The warmest sea water temperatures in Ko Samui are found in June when they peak at 30° and lowest in December when they dip to 27°.

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.

Annual Rainfall for Ko Samui

The wettest month in Ko Samui is November with 26.5cm of rain and October has the most days of rain with 23 days with some rain, a very wet time to visit the beach.

The driest month in Ko Samui is February with 1.3cm of rain and the least days of rain with 3 days with some rain, a very dry time to visit the beach.

Annual Humidity for Ko Samui

The most humid month in Ko Samui is April with a dew point (an indicator of humidity) of 26° 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 Ko Samui is January with a dew point of 24° which is very uncomfortable and fairly oppressive unless you are on a beach. At night you would most likely require airconditioning.

Annual Wind Speed for Ko Samui

The most windy month in Ko Samui is July when the average maximum windspeed is 25kmh and the average wind speed is 11kmh.

The least windy month in Ko Samui is April when the average maximum windspeed is 22kmh and the average wind speed is 11kmh.

Monthly Averages

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