Swimming on the island of Koh Samui in september 2025 Sea temperature by city in september
Do you want to go to the beach on the island of Koh Samui in september 2025? Is it the right month to go for pleasant temperatures and staying in the water for a long time? The answer is on this page with the sea temperatures in september on the island of Koh Samui by city and our opinion on the chances of enjoying pleasant sea conditions.
Sea temperature on the island of Koh Samui in september 2025
Here, find the average sea temperature on the island of Koh Samui in september in several coastal cities.
85°F
min: 83°F / max: 86°F
Bang Kao (Laem Sor beach)
85°F
min: 83°F / max: 87°F
Bophut
85°F
min: 83°F / max: 87°F
Choeng Mon
85°F
min: 83°F / max: 87°F
Koh Madsum
85°F
min: 83°F / max: 86°F
Koh Phaluai
85°F
min: 83°F / max: 86°F
Koh Taen
85°F
min: 83°F / max: 87°F
Lamai beach
85°F
min: 83°F / max: 86°F
Lipa Noi
85°F
min: 83°F / max: 87°F
Maenam
85°F
min: 83°F / max: 87°F
Nathon
85°F
min: 83°F / max: 87°F
Where should you go swimming on the island of Koh Samui in the month of september?
Swimming on the island of Koh Samui in september is ideal
In september on the island of Koh Samui swimming conditions are generally the same everywhere.
In september in Chaweng Beach, Bang Kao (Laem Sor beach), Bophut, Choeng Mon, Koh Madsum, Koh Phaluai, Koh Taen, Lamai beach, Lipa Noi, Maenam and Nathon, swimming conditions are perfect! With water reaching a maximum of 86°F and an average of 85°F, going in the water (and staying there!) feels great.
Where to go swimming on the island of Koh Samui in september: the map of sea temperatures
ideal swimming 
pleasant swimming 
cool swimming 
cold swimming 
freezing swimmingWater temperature and seasonal norms in september
Chaweng Beach
| September | |||
| Average sea temperature | 85°F | ||
| Minimum sea temperature | 83°F | ||
| Maximum sea temperature | 86°F | ||
| Average outside temperature | 85°F | ||
| Maximum outside temperature | 86°F | ||
| Minimum outside temperature | 83°F | ||
| Precipitation | 7.4in | ||
| Number of days of precipitation | 12 jour(s) (41%) | ||
| Cloud cover | 43% | ||
| Our opinion | ideal swimming |
More information on swimming in Chaweng Beach in september
Bang Kao (Laem Sor beach)
| September | |||
| Average sea temperature | 85°F | ||
| Minimum sea temperature | 83°F | ||
| Maximum sea temperature | 87°F | ||
| Average outside temperature | 85°F | ||
| Maximum outside temperature | 86°F | ||
| Minimum outside temperature | 83°F | ||
| Precipitation | 7.4in | ||
| Number of days of precipitation | 12 jour(s) (41%) | ||
| Cloud cover | 43% | ||
| Our opinion | ideal swimming |
Bophut
| September | |||
| Average sea temperature | 85°F | ||
| Minimum sea temperature | 83°F | ||
| Maximum sea temperature | 87°F | ||
| Average outside temperature | 85°F | ||
| Maximum outside temperature | 86°F | ||
| Minimum outside temperature | 83°F | ||
| Precipitation | 7.4in | ||
| Number of days of precipitation | 12 jour(s) (41%) | ||
| Cloud cover | 43% | ||
| Our opinion | ideal swimming |
Choeng Mon
| September | |||
| Average sea temperature | 85°F | ||
| Minimum sea temperature | 83°F | ||
| Maximum sea temperature | 87°F | ||
| Average outside temperature | 85°F | ||
| Maximum outside temperature | 86°F | ||
| Minimum outside temperature | 83°F | ||
| Precipitation | 7.4in | ||
| Number of days of precipitation | 12 jour(s) (41%) | ||
| Cloud cover | 43% | ||
| Our opinion | ideal swimming |
Koh Madsum
| September | |||
| Average sea temperature | 85°F | ||
| Minimum sea temperature | 83°F | ||
| Maximum sea temperature | 86°F | ||
| Average outside temperature | 85°F | ||
| Maximum outside temperature | 86°F | ||
| Minimum outside temperature | 83°F | ||
| Precipitation | 7.4in | ||
| Number of days of precipitation | 12 jour(s) (41%) | ||
| Cloud cover | 43% | ||
| Our opinion | ideal swimming |
List of coastal cities on the island of Koh Samui
| Chaweng Beach in september | ideal swimming |
| Bang Kao (Laem Sor beach) in september | ideal swimming |
| Bophut in september | ideal swimming |
| Choeng Mon in september | ideal swimming |
| Koh Madsum in september | ideal swimming |
| Koh Phaluai in september | ideal swimming |
| Koh Taen in september | ideal swimming |
| Lamai beach in september | ideal swimming |
| Lipa Noi in september | ideal swimming |
| Maenam in september | ideal swimming |
| Nathon in september | ideal swimming |