September 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

What is the temperature in September in Ko Samui?

In September, the average high-temperature is 30.5°C (86.9°F), and the average low-temperature is 24.8°C (76.6°F).

How much does it rain in Ko Samui in September?

In September, in Ko Samui, Thailand, the rain falls for 16 days. Throughout September, 121.7mm (4.8") of precipitation is accumulated.
Average temperature in September - Ko Samui, Thailand
  • Average high temperature in September: 30.5°C

The warmest month (with the highest average high temperature) is April (32.6°C).
The month with the lowest average high temperature is January (29°C).

  • Average low temperature in September: 24.8°C

The month with the highest average low temperature is April (26.1°C).
The coldest month (with the lowest average low temperature) is December (23.9°C).

Average humidity in September - Ko Samui, Thailand
  • Average humidity in September: 80%

Months with the highest relative humidity are October and November (85%).
Months with the lowest relative humidity are June, July and August (78%).

Average rainfall in September - Ko Samui, Thailand
  • Average rainfall in September: 121.7mm

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 in September - Ko Samui, Thailand
  • Average rainfall days in September: 16 days

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 in September - Ko Samui, Thailand
  • Average sea temperature in September: 29.2°C

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 in September / Average sunshine in September - Ko Samui, Thailand
  • Average daylight in September: 12.2h

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

  • Average sunshine in September: 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 in September - Ko Samui, Thailand
  • Average UV index in September: 12

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).

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