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Weather in Ko Samui for September 2025

Your guide to Ko Samui weather in September - trends and predictions

    Temperatures

  • Until now, September 2025 in Ko Samui is slightly cooler than the historical average by -0.6 °C.

  • The forecast for the next days in Ko Samui predicts temperatures to be around 29 °C, close to the historical average.

  • In general, the average temperature in Ko Samui at the beginning of September is 29 °C. As the month progressed, temperatures tended to remain steady, reaching an average of 29 °C by the end of September.

    • Rain 🌧️

  • Ko Samui experiences heavy rainfall in September, with over 20 rainy days and an average total precipitation 157.1 mm.

    • More

  • Is September a good time to visit Ko Samui? check out the best time to travel to Ko Samui page.

  • New! Chat with our AI weatherman - it’s amazing and free.

Average dry days
1
Dry days
Average rainy days
29
Rainy days
Average snowy days
0
Snow days
Average temperatures
28°/27°
Temperatures
Average wind speed
25 km/h
Avg max wind
Average humidity
74 %
Avg humidity

Ko Samui Weather September

Move between months or click on a day
August
October
Mon.Tue.Wed.Thu.Fri.Sat.Sun.
1
Moderate or heavy rain shower
29°
2
Moderate or heavy rain shower
29°
3
Light rain shower
29°
4
Patchy rain possible
29°
5
Cloudy
29°
6
Light rain shower
29°
7
Heavy rain at times
29°
8
Patchy rain possible
29°
9
Patchy rain possible
29°
10
Patchy rain possible
29°
11
Moderate rain at times
29°
12
Patchy rain possible
29°
13
Moderate or heavy rain shower
29°
14
Moderate or heavy rain shower
28°
15
Moderate or heavy rain shower
28°
16
Patchy rain possible
29°
17
Patchy rain possible
30°
18
Moderate rain
29°
19
Patchy rain possible
28°
20
Patchy rain possible
31°
21
Patchy rain possible
30°
22
Partly cloudy
30°
23
Patchy rain possible
30°
24
Patchy rain possible
29°
25
Patchy rain possible
29°
26
Partly cloudy
29°
27
Patchy rain possible
29°
28
Patchy rain possible
29°
29
Sunny
29°
30
Patchy rain possible
29°

Temperatures trend during September in Ko Samui

See the weather trend as well as the moving average line

September weather in Ko Samui day by day

Click on a date for more information
August October
Date Weather Temperatures Rain UV More
1 Sept. Moderate or heavy rain shower
Moderate or heavy rain shower
 29° /26° 9.6 mm 6
2 Sept. Moderate or heavy rain shower
Moderate or heavy rain shower
 29° /27° 3.8 mm 6
3 Sept. Light rain shower
Light rain shower
 29° /25° 5.1 mm 6
4 Sept. Patchy rain possible
Patchy rain possible
 29° /26° 3.6 mm 6
5 Sept. Cloudy
Cloudy
 29° /26° 10.6 mm 6
6 Sept. Light rain shower
Light rain shower
 29° /26° 5.4 mm 6
7 Sept. Heavy rain at times
Heavy rain at times
 29° /26° 6.8 mm 6
8 Sept. Patchy rain possible
Patchy rain possible
 29° /27° 2.4 mm 6
9 Sept. Patchy rain possible
Patchy rain possible
 29° /27° 4.8 mm 6
10 Sept. Patchy rain possible
Patchy rain possible
 29° /27° 3.6 mm 6
11 Sept. Moderate rain at times
Moderate rain at times
 29° /27° 1.9 mm 6
12 Sept. Patchy rain possible
Patchy rain possible
 29° /27° 0.7 mm 6
13 Sept. Moderate or heavy rain shower
Moderate or heavy rain shower
 29° /26° 6.4 mm 6
14 Sept. Moderate or heavy rain shower
Moderate or heavy rain shower
 28° /26° 10.5 mm 6
15 Sept. Moderate or heavy rain shower
Moderate or heavy rain shower
 28° /26° 5.1 mm 6
16 Sept. Patchy rain possible
Patchy rain possible
 29° /28° 1.5 mm 2.2
17 Sept. Patchy rain possible
Patchy rain possible
 30° /28° 1.3 mm 2.9
18 Sept. Moderate rain
Moderate rain
 29° /27° 7.1 mm 1.6
19 Sept. Patchy rain possible
Patchy rain possible
 28° /26° 1.7 mm 1.2
20 Sept. Patchy rain possible
Patchy rain possible
 31° /28° 0.4 mm 2.8
21 Sept. Patchy rain possible
Patchy rain possible
 30° /28° 0.6 mm 6
22 Sept. Partly cloudy
Partly cloudy
 30° /28° 0.1 mm 7
23 Sept. Patchy rain possible
Patchy rain possible
 30° /28° 0.4 mm 6
24 Sept. Patchy rain possible
Patchy rain possible
 29° /28° 1.3 mm 6
25 Sept. Patchy rain possible
Patchy rain possible
 29° /28° 1.3 mm 6
26 Sept. Partly cloudy
Partly cloudy
 29° /29° 0 mm 7
27 Sept. Patchy rain possible
Patchy rain possible
 29° /29° 1.4 mm 6
28 Sept. Patchy rain possible
Patchy rain possible
 29° /28° 3 mm 6
29 Sept. Sunny
Sunny
 29° /29° 0 mm 7
30 Sept. Patchy rain possible
Patchy rain possible
 29° /27° 3.6 mm 6
Next
Important Notice
Our weather forecast for Ko Samui in September is based on the analysis of historical data rather than real-time forecast models. While this provides a general overview, weather conditions can change. We recommend that you check the Ko Samui forecast closer to your planned date for the most up-to-date weather information.
Change Month
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Ko Samui weather in September vs August vs October

Compare September weather in Ko Samui with the previous and following months. See how temperature, rainfall, wind, and other conditions change throughout the year to help you plan your visit.
AugustSeptemberOctober
WeatherPatchy rain possible
Patchy rain possible
Patchy rain possible
Patchy rain possible
Patchy rain possible
Patchy rain possible
Temperatures29°/27°28°/27°28°/27°
Rainfall130 mm157 mm274 mm
Wind21.7 km/h24.6 km/h18.5 km/h
Humidity73%74%75%
Rainy days30 days29 days31 days
Dry days1 days1 days0 days

Planning a trip to Ko Samui? Discover the best time to visit

Ko Samui in September - FAQ

What are the expected maximum and minimum temperatures in Ko Samui during September?
During September, expect a variety of temperatures with highs around 28° and lows near 27°, suitable for diverse activities and preferences.
How much rainfall should be expected in Ko Samui during September?
Significant rainfall exceeding 157.1 mm is expected in Ko Samui during September, occurring over more than 29 days. Preparing for wet conditions is recommended in your planning.
What are the typical wind conditions in Ko Samui during September?
The average wind speed in Ko Samui during September is 25 km/h, suggesting breezy to windy conditions, depending on your activities.

What to pack to Ko Samui in September?

As you prepare for your trip to Ko Samui in September, it's important to consider the typical weather patterns for the time of year. Below is a carefully tailored packing list to ensure that your time in Ko Samui, during September, is comfortable and enjoyable, regardless of the weather conditions.

  • Clothing
    • Lightweight Clothing: T-shirts, blouses, shorts, skirts
    • Rain Gear: Lightweight, waterproof clothing
  • Footwear
    • Waterproof Shoes
  • Accessories
    • Sunglasses: For sun protection
    • Sun Hats: Wide-brimmed hats for sun protection in warm weather
    • Umbrellas/Raincoats: For rainy days
  • Personal Items
    • Sunscreen: High SPF for sunny destinations
    • Lip Balm with SPF: To protect against chapped lips

September rainfall patterns in Ko Samui

Explore the daily rainfall trends and prepare for Ko Samuis September weather 💧

UV exposure in Ko Samui during September

Stay informed about UV levels for safe outdoor activities throughout the month of September ☀️

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Location coordinates Where is Ko Samui?

Get accurate weather forecasts for Ko Samui, located at latitude 9.536 and longitude 99.936. Stay updated with localized weather information tailored for Ko Samui.

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