Ko Samui
Thailand
Long-term weather forecast
Long-term weather forecast

Monthly weather forecast and climate
Ko Samui, Thailand

The scenic view of the striking Angthong National Marine Park in Ko Samui, Thailand, calm clear water all around
The scenic view of the striking Angthong National Marine Park in Ko Samui, Thailand, calm clear water all around
The best months for a swim in Ko Samui, Thailand, are February and March, with a perfect temperature - varying between 25°C (77°F) and 29°C (84.2°F), and scarce rainfall.
January, like December, in Ko Samui, Thailand, is another warm winter month, with temperature in the range of an average low of 24.2°C (75.6°F) and an average high of 29°C (84.2°F). January is the coldest month, with an average high-temperature of 29°C (84.2°F) and an average low-temperature of 24.2°C (75.6°F). The average heat index is estimated at a very hot 35.4°C (95.7°F). Weather in January »

February, the last month of the winter, in Ko Samui, is also a moderately hot month, with average temperature fluctuating between 25°C (77°F) and 29.4°C (84.9°F). An excellent water temperature of 28.1°C (82.6°F) and only 5 rainfall days, with 54.4mm (2.1") of accumulated rainfall, makes February a prime for swimming and other water activities. Weather in February »

March, the first month of the spring, in Ko Samui, is a tropical month, with average temperature varying between 25.6°C (78.1°F) and 30.6°C (87.1°F). An excellent water temperature of 28.8°C (83.8°F) and only 4 rainfall days, with 80.8mm (3.2") of accumulated rainfall, makes March a prime for swimming and other water activities. Weather in March »

April, like March, is a hot spring month in Ko Samui, Thailand, with average temperature varying between 26.1°C (79°F) and 32.6°C (90.7°F). The warmest month is April, with an average high-temperature of 32.6°C (90.7°F) and an average low-temperature of 26.1°C (79°F). In April, the average heat index is appraised at a blazing hot 47.1°C (116.8°F). Weather in April »

The last month of the spring, May, is another tropical month in Ko Samui, Thailand, with temperature in the range of an average high of 32.5°C (90.5°F) and an average low of 25.7°C (78.3°F). In May, the average high-temperature is practically the same as in April - a still hot 32.5°C (90.5°F). Weather in May »

June, the first month of the summer, in Ko Samui, is still a tropical month, with average temperature varying between 32.2°C (90°F) and 25.5°C (77.9°F). In Ko Samui, the average high-temperature is almost the same as in May - a still tropical 32.2°C (90°F). Weather in June »

July, like June, is another tropical summer month in Ko Samui, Thailand, with temperature in the range of an average low of 25.2°C (77.4°F) and an average high of 32.1°C (89.8°F). In Ko Samui, the average high-temperature is relatively the same as in June - a still tropical 32.1°C (89.8°F). Weather in July »

The last month of the summer, August, is another tropical month in Ko Samui, Thailand, with average temperature fluctuating between 25.2°C (77.4°F) and 31.7°C (89.1°F). In August, the average high-temperature is practically the same as in July - a still hot 31.7°C (89.1°F). Weather in August »

September, the first month of the autumn, in Ko Samui, is still a hot month, with average temperature varying between 24.8°C (76.6°F) and 30.5°C (86.9°F). In Ko Samui, the average high-temperature in September is relatively the same as in August - a still hot 30.5°C (86.9°F). Weather in September »

October, the same as September, is another warm autumn month in Ko Samui, Thailand, with average temperature varying between 24.3°C (75.7°F) and 29.6°C (85.3°F). In October, the average high-temperature is relatively the same as in September - a warm 29.6°C (85.3°F). Weather in October »

The last month of the autumn, November, is also a moderately hot month in Ko Samui, Thailand, with average temperature fluctuating between 29.2°C (84.6°F) and 24.1°C (75.4°F). In November, the average high-temperature is practically the same as in October - a still moderately hot 29.2°C (84.6°F). Weather in November »

The first month of the winter, December, is a hot month in Ko Samui, Thailand, with average temperature ranging between max 32°C (89.6°F) and min 23.9°C (75°F). In Ko Samui, the average high-temperature is essentially the same as in November - a tropical 32°C (89.6°F). Weather in December »

What is the coldest month in Ko Samui?

The coldest month is January, with an average high-temperature of 29°C (84.2°F) and an average low-temperature of 24.2°C (75.6°F).

How many days does it rain in Ko Samui?

Throughout the year, in Ko Samui, there are 160 rainfall days, and 1960.1mm (77.2") of precipitation is accumulated.

When is the sea coldest in Ko Samui?

With an average sea temperature of 27.8°C (82°F), January is the month with the coldest seawater.

What is the month with the shortest days in Ko Samui?

January and December, with an average of 11.6h of daylight, are months with the shortest days in Ko Samui.

What is the driest month in Ko Samui?

The month with the least rainfall is February when the rain falls for 5 days and typically collects 54.4mm (2.1") of precipitation.

What month has the most sunshine in Ko Samui?

With an average of 9h of sunshine, February has the most sunshine of the year.

When is the highest UV index in Ko Samui?

Months with the highest UV index in Ko Samui are February through October, with an average maximum UV index of 12.

What is the warmest month in Ko Samui?

With an average high-temperature of 32.6°C (90.7°F) and an average low-temperature of 26.1°C (79°F), April is the warmest month.

When is the sea warmest in Ko Samui?

The month with the warmest seawater in Ko Samui, Thailand, is May, with an average sea temperature of 30.1°C (86.2°F).

What is the month with the least sunshine in Ko Samui?

Months with the least sunshine in Ko Samui, Thailand, are May through December, with an average of 6h of sunshine.

What is the least humid month in Ko Samui?

June through August, with an average relative humidity of 78%, are the least humid months in Ko Samui, Thailand.

When are the longest days in Ko Samui?

June has the longest days of the year, with an average of 12.7h of daylight.

What are the most humid months in Ko Samui?

Months with the highest humidity in Ko Samui are October and November, with an average relative humidity of 85%.

What is the rainiest month in Ko Samui?

November is the month with the most rainfall in Ko Samui, Thailand. Rain falls for 20 days and accumulates 506.6mm (19.9") of precipitation.

What is the month with the lowest UV index in Ko Samui?

With an average maximum UV index of 10, December is the month with the lowest UV index in Ko Samui, Thailand.
Average temperature - Ko Samui, Thailand
Average humidity - Ko Samui, Thailand
Average rainfall - Ko Samui, Thailand

The wettest month (with the highest rainfall) is November (506.6mm).
The driest month (with the lowest rainfall) is February (54.4mm).

Average rainfall days - Ko Samui, Thailand

Months with the highest number of rainy days are October and November (20 days).
The month with the lowest number of rainy days is March (4 days).

Average sea temperature - Ko Samui, Thailand

The best month for swimming (with the highest average sea temperature) is May (30.1°C).
The coldest month (with the lowest average sea temperature) is January (27.8°C).

Average daylight / Average sunshine - Ko Samui, Thailand

The month with the longest days is June (Average daylight: 12.7h).
Months with shortest days are January and December (Average daylight: 11.6h).

The month with most sunshine is February (Average sunshine: 9h).
Months with least sunshine are May, June, July, August, September, October, November and December (Average sunshine: 6).

Average UV index - Ko Samui, Thailand

Months with the highest UV index are February, March, April, May, June, July, August, September and October (UV index 12).
The month with the lowest UV index is December (UV index 10).