Koh Samui weather in September

September is not a good time to visit Koh Samui as it falls during the hot, wet season.

You can expect very hot, sunny days interspersed with late-afternoon tropical downpours. Daytime temperatures average 29°C (84°F).

How hot is it in Koh Samui in September?
Daytime temperatures in Koh Samui in September reach an average high of 32°C (89°F) with high heat and humidity, falling to a night-time low of 27°C (80°F).

How sunny is it in Koh Samui in September?
There are normally six hours of bright sunshine each day in Koh Samui in September – that's around 47% of daylight hours.

Sunrise & sunset in September?
Sunrise is around 6:10am with sunset around 6:20pm.

How warm is the sea around Koh Samui in September?
The average sea temperature in Koh Samui in September is 29°C (84°F).

Does it rain in Koh Samui in September?
There are usually 10 days with some rain in Koh Samui in September; the average monthly rainfall is 122mm (4.8in).

The wet season typically lasts from May to mid-December, with a greater than 37% chance of a given day being a wet day. During this time you can expect frequent but brief heavy downpours interspersed with sunny skies.

How windy is it in Koh Samui in September?
September sees an average hourly wind speed of 16 kilometres per hour (10 mph; 8.6 knots).

What to do in Koh Samui in September?
Weather conditions in September are good for swimming, snorkelling, scuba diving and kayaking. It’s also a good time to explore Koh Samui on foot or by elephant.

Local holidays?
None. September is considered the low season in Koh Samui, with more reasonable hotel prices and less people on the beaches.

Koh Samui weather in September

Temperature icon High Temp: 32°C (89°F)
temperature icon Low Temp: 27°C (80°F)
sun icon Sunshine: 6 hours per day
Moderately hot icon
Daylight: 12 hours per day
wind icon Wind speed: 16 km/h (10 mph; 8.6 knots)
umbrella icon Wet Days: 10 days with some rain
rain cloud Rainfall: 122 mm (4.8 in) per month
High heat icon Comfort Level: High heat & 80% humidity
Moderately hot icon
UV Index: Extreme
swimming icon Sea Temp: 29°C (84°F)
Koh Samui, Thailand

Best time to visit Koh Samui

The best time to visit Koh Samui is during January and February.

However, anytime during the dry season from mid-December through to early-March is good, with daytime temperatures averaging 28°C (82°F).

For more climate info: Koh Samui weather overview

Koh Samui weather by month

Source: Meteorological data for Koh Samui is based on weather statistics gathered for the 10-year period 2012 to 2021 by the Thai Meteorological Department at the closest weather station: Koh Samui Airport, (USM), located about 2km north of Chaweng.

Advice on the best time to visit a particular destination is based on average local weather statistics, when the weather conditions are generally better than at other times of the year. We consider high and low temperatures, risk of rain (and thunderstorms, etc.), amount of sunshine and sea temperature. For general outdoor activities we favour clear, rainless days with a temperature range between 18°C (64°F) and 27°C (80°F); and for hot-weather activities we favour clear, rainless days with a temperature range between 24°C (75°F) and 32°C (89°F). Often, the best times to visit correspond to high season and therefore involve higher prices.

Latest update: Koh Samui weather in April: 12 June, 2024

Disclaimer: The information on this site is provided as is, without any assurances as to its accuracy or suitability for any purpose. Weather data and conditions at any given location and time are unpredictable and variable. We assume no responsibility and can not be held legally responsible for any decisions made on the basis of the information presented on this site.