Koh Samui, THAILAND and its best beaches
Climate - Temperatures and rainfall - South China Sea
Koh Samui: Temperatures during the day, at night, rain and bathing conditions
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January Day temperature  85°F / 29°C |
Night temp.  76°F / 24°C |
Bathing temperature  83°F / 28°C |
Rain  138 mm |
Conditions  
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February Day temperature 85°F / 29°C |
Night temp. 76°F / 24°C |
Bathing temperature 85°F / 29°C |
Rain 052 mm |
Conditions  
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March Day temperature 88°F / 31°C |
Night temp. 77°F / 25°C |
Bathing temperature 86°F / 30°C |
Rain 077 mm |
Conditions
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April Day temperature 90°F / 32°C |
Night temp. 77°F / 25°C |
Bathing temperature 86°F / 30°C |
Rain 076 mm |
Conditions
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May Day temperature 90°F / 32°C |
Night temp. 77°F / 25°C |
Bathing temperature 86°F / 30°C |
Rain 146 mm |
Conditions
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June Day temperature 90°F / 32°C |
Night temp. 77°F / 25°C |
Bathing temperature 86°F / 30°C |
Rain 112 mm |
Conditions
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July Day temperature 90°F / 32°C |
Night temp. 76°F / 24°C |
Bathing temperature 85°F / 29°C |
Rain 122 mm |
Conditions
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August Day temperature 90°F / 32°C |
Night temp. 77°F / 25°C |
Bathing temperature 85°F / 29°C |
Rain 118 mm |
Conditions
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September Day temperature 88°F / 31°C |
Night temp. 76°F / 24°C |
Bathing temperature 85°F / 29°C |
Rain 114 mm |
Conditions
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October Day temperature 86°F / 30°C |
Night temp. 76°F / 24°C |
Bathing temperature 85°F / 29°C |
Rain 290 mm |
Conditions 
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November Day temperature 85°F / 29°C |
Night temp. 76°F / 24°C |
Bathing temperature 85°F / 29°C |
Rain 495 mm |
Conditions
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December Day temperature 85°F / 29°C |
Night temp. 76°F / 24°C |
Bathing temperature 83°F / 28°C |
Rain 209 mm |
Conditions
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Thailand : climate and when to go to Koh samui
The climate in Phuket and Koh Samui is very pleasant throughout the year, with temperatures varying between 77°F at night and 93°F during the day.
There are three seasons, the hot season from February to May, the rainy season from the end of September to November, and the "cool" season from October to January.
From February to October it average 32 to 38 degrees, but from July to September there may be some showers, but only for a few hours. The rainy season is often summed up in some "refreshing" tropical rain showers followed by the return of the sun. The climate is tropical so very wet throughout the year, but Samui always remains refreshed with a pleasant sea breeze coming from the Gulf.
| January Acceptable |
February Pecfect |
March Pecfect |
April Pecfect |
May Risky |
June Acceptable |
July Acceptable |
August Acceptable |
September Acceptable |
October Avoid |
November Avoid |
December Risky |
When to go? The hottest month for the beach, lazing around and swimming is April. Check the precipitations because showers are possible but the sun returns quickly, otherwise other periods are possible. The coolest month is January, if you can not stand the heat too much. The driest month of the year is February, if you do not like the rain at all.
Click on
Phuket -
Koh Samui to display its climate.
Graphs and temperature curves with average precipitation over the year
Precipitation, rainfall, cyclone: THAILAND
Temperatures of bathing water around Koh Samui
Landmarks
Perfect conditions to enjoy the beach.
Favorable conditions for enjoying the beach. Cloudy with sunny spells and thunderstorms. Very strong tropical or monsoon rains.
Months at risk of cyclones with alerts level 1 to 5. Nice swimming at more than 26°C / 79°F. Everything is perfect for traveling.No cyclone risk for this country
South China Sea
Climate April 2025
Koh Samui sunshine in summer and winter
The sun at its zenith, that means well perpendicular to the surface of the Earth, sending 100% of radiation and heat. Koh Samui receives in winter (january), 83% of sun power and 97% during summer time (july).
The average temperature and sunshine deviations between summer and winter are 14%. This small gap means that the temperature at sea does not really vary and that the sea remains warm enough in summer and winter. The air is also hot all year round without great thermal amplitude.
Average temperatures and rainfall for a stay in April
On the left, the averages observed every month of April on the Thailand beaches. The trends for next month are, the same daytime average temperatures, a bathing water in South China Sea remaining at a stable temperature, more abundant rains with nights as temperate as this month.
Sunset and sunrise times for THAILAND
Local time : April 2025, Saturday 19, 06:49 AM
Sunrise time : 06:09 am, point A
Sunset time : 6:27 pm, point B
Duration of daylight : 12:18 / 24:00
Jet lag : GMT+7
The average monthly UV index of THAILAND
What is the period of mosquitoes virulence over the year?
Weather forecast for Koh Samui
Here are the current 5-day forecasts for Ban Bang Rak / Koh Samui. Temperatures are spaced 3 hours apart for each day. The summary of the state of the sky gives the trend of the week. The sea temperature at is a monthly average. In lagoons or seashores where the bathing water is shallow, you can add some degrees.
Sunday
April 20, 2025
8 am
83.9°F
29°C
Overcast clouds
Humidity 72%
Sea 86°F/30°C
Sunday
April 20, 2025
11 am
84.5°F
30°C
Overcast clouds
Humidity 71%
Sea 86°F/30°C
Sunday
April 20, 2025
2 pm
84.6°F
30°C
Overcast clouds
Humidity 71%
Sea 86°F/30°C
Sunday
April 20, 2025
5 pm
84.4°F
30°C
Scattered clouds
Humidity 72%
Sea 86°F/30°C
Sunday
April 20, 2025
8 pm
84°F
29°C
Scattered clouds
Humidity 73%
Sea 86°F/30°C
Sunday
April 20, 2025
11 pm
83.1°F
29°C
Light rain
Humidity 76%
Sea 86°F/30°C
Monday
April 21, 2025
8 am
83.6°F
29°C
Scattered clouds
Humidity 74%
Sea 86°F/30°C
Monday
April 21, 2025
11 am
84.9°F
30°C
Light rain
Humidity 73%
Sea 86°F/30°C
Monday
April 21, 2025
2 pm
84.6°F
30°C
Scattered clouds
Humidity 71%
Sea 86°F/30°C
Monday
April 21, 2025
5 pm
84.8°F
30°C
Few clouds
Humidity 69%
Sea 86°F/30°C
Monday
April 21, 2025
8 pm
84.2°F
29°C
Scattered clouds
Humidity 70%
Sea 86°F/30°C
Monday
April 21, 2025
11 pm
84.2°F
29°C
Overcast clouds
Humidity 71%
Sea 86°F/30°C
Tuesday
April 22, 2025
8 am
84°F
29°C
Overcast clouds
Humidity 73%
Sea 86°F/30°C
Tuesday
April 22, 2025
11 am
85°F
30°C
Scattered clouds
Humidity 67%
Sea 86°F/30°C
Tuesday
April 22, 2025
2 pm
84.8°F
30°C
Broken clouds
Humidity 70%
Sea 86°F/30°C
Tuesday
April 22, 2025
5 pm
84.9°F
30°C
Overcast clouds
Humidity 70%
Sea 86°F/30°C
Tuesday
April 22, 2025
8 pm
84.8°F
30°C
Overcast clouds
Humidity 70%
Sea 86°F/30°C
Tuesday
April 22, 2025
11 pm
83.1°F
29°C
Light rain
Humidity 77%
Sea 86°F/30°C
Wednesday
April 23, 2025
8 am
84.2°F
29°C
Broken clouds
Humidity 73%
Sea 86°F/30°C
Wednesday
April 23, 2025
11 am
84.5°F
30°C
Broken clouds
Humidity 69%
Sea 86°F/30°C
Wednesday
April 23, 2025
2 pm
85.2°F
30°C
Broken clouds
Humidity 68%
Sea 86°F/30°C
Wednesday
April 23, 2025
5 pm
85°F
30°C
Light rain
Humidity 70%
Sea 86°F/30°C
Wednesday
April 23, 2025
8 pm
84.7°F
30°C
Light rain
Humidity 72%
Sea 86°F/30°C
Wednesday
April 23, 2025
11 pm
82.9°F
29°C
Light rain
Humidity 74%
Sea 86°F/30°C
Weather uncertainties 2025 to go to Koh Samui ?
When traveling in the tropics as a seaside, rain is not welcome. If you see this indicator, with possible storms, that does not mean that it will rain all day long. When we observe the local rainfall, it is either really zero or very weak. Meteorologists prefer to be pessimistic. So observe below, the skies photographed during a week announced stormy in Asia. It did not rain once. I invite you to integrate this parameter before going to Koh Samui for a good trip to the sun!
