Water temperature in Koh Samui

This data the coastal Koh Samui sea water temperature today, tomorrow and the upcoming days. Besides, you can also get information about the weather and surf forecast, as well as the data on sunrise / sunset and moonrise / moonset at a given point on any given day.

Current sea temperature in Koh Samui

Water temperature in Koh Samui today is 29.8°C. Based on our historical data over a period of ten years, the warmest water in this day in the Gulf of Thailand near Koh Samui was recorded in 2022 and was 30.1°C, and the coldest was recorded in 2012 at 28.1°C. Sea water temperature in Koh Samui is expected to drop to 29.6°C in the next 10 days. September average water temperature in Koh Samui is 29.6°C, the minimum temperature is 27.9°C, and the maximum is 31°C.

The swimming season in Koh Samui lasts from January to December, twelve months per year! During those months, Koh Samui water temperature does not drop below 20°C and therefore suitable for comfortable swimming. The average water temperature in Koh Samui in winter reaches 28.2°C, in spring 30.1°C, in summer the average temperature rises to 30°C, and in autumn it is 29.3°C.

Koh Samui water temperature now

The sea salinity in Koh Samui is 31.92‰, and the average salinity of the World Ocean is 35‰.

Surf Forecast in Koh Samui for today

Another important indicators for a comfortable holiday on the beach are the presence and height of the waves, as well as the speed and direction of the wind. Please find below data on the swell size for Koh Samui. We calculate the swell size based on the mean wave height (trough to crest) of each third highest wave. For more information on surf forecasts for the next ten days, please visit sea state forecast Koh Samui. Data in table shown for 13 September 2025, time in GMT 0 format (you can change the time zone on the sea state forecast page)

Surf report in Koh Samui

Koh Samui weather forecast

Current temperature and weather

Data in a table show Koh Samui temperature today (13 September 2025). For more information and forecast for a few days, go to the weather forecast Koh Samui.

0-3 h	3-6 h	6-9 h	9-12 h
28.6°C	27.3°C	26°C	26.5°C

12-15 h	15-18 h	18-21 h	21-24 h
26.4°C	26.9°C	27.5°C	27.7°C

Koh Samui water temperature by month

These figures shows the average, minimum and maximum monthly sea temperature in Koh Samui. In addition to the table values, the graph below displays of changes average surface temperature during the year. Values are calculated based on the data over the past 10 years. Using them, you can check the water temperature in Koh Samui on any day of this period that interests you. Click on the month link and you will see a table for each day, or alternatively you can view the temperature curve of the month and select 2 different years you want to compare, either in a table or as a curve

Chart monthly average water temperature in Koh Samui

The nearest beaches and cities from Koh Samui with the water temperature today, as well as the air temperature and the state of the weather during the day and the average wave height for today

	Water	Weather		Wave
Lamai Beach	29.9°C	27°C		0.08 m
Taling Ngam Beach	29.9°C	27°C		0.08 m
Lipa Noi	29.9°C	27°C		0.08 m
Chaweng Beach	29.7°C	27°C		0.09 m
Mae Nam	29.7°C	27°C		0.09 m
Choeng Mon Beach	29.6°C	27°C		0.09 m
Khanom Beach	29.5°C	26°C		0.04 m
Bo Phut Beach	29.6°C	27°C		0.08 m
Mae Nam Beach	29.6°C	27°C		0.08 m
Haad Rin	29.6°C	27°C		0.09 m

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Ko Samui

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Our report for Koh Samui is compiled using satellite data together with in-situ observations to get the most reliable daily data of sea surface temperatures, surf forecasts, current temperatures and weather forecasts.