Koh Samui weather in August
Temperature, sea and sunshine in August: long-term averages from 30 years of weather data, not a forecast.
Holiday weather in August
Good
Best time to visit: January – April
What is the weather like in Koh Samui in August?
In August, Koh Samui is hot: daytime highs average 30 °C, and even at night it stays warm at around 27 °C. The sea averages 29.4 °C – almost as warm as a bath. The sun shines for around 7 hours a day. It is the rainy season: rain falls on about 21 days, totalling 124 mm. On about 9 days the thermometer climbs to 30 °C or more. The air is often humid and muggy. All in all, August is a good month for a holiday in Koh Samui.
August compared
How the weather changes from July to September. Tap a month to open it.
| JulyJul | AugustAug | SeptemberSep | |
|---|---|---|---|
| Score | 71 | 72 | 70 |
| Day | 30° | 30° | 29° |
| Night | 27° | 27° | 27° |
| Sea | 30° | 29° | 29° |
| Sun | 6 h | 7 h | 6 h |
| Rain days | 21 | 21 | 25 |
More details for August
- Daylight
- 12 h 27 min06:12 – 18:38
- UV index
- 13 · extremeclear sky, noon (estimate)
- Muggy days
- 31 daysdew point 18 °C or more
- Wind
- 16 km/haverage daily peak
- Cloud cover
- 87 %on average
- Hot days
- 9 days30 °C or more
- Time zone
- UTC+7Asia/Bangkok
How the score comes together
- Temperatureweight 35 %100 %
- Seaweight 25 %100 %
- Sunshineweight 20 %58 %
- Few rainy daysweight 20 %0 %
Each factor is rated from 0 to 100 % and weighted for the travel style “Sun, sea & sand”.
What to pack in August
- Swimwear
- Sunscreen
- Sunglasses & sun hat
- Light, breathable clothes
- Water bottle – drink plenty
- Insect repellent
- Rain jacket or umbrella
Koh Samui in August: quick answers
Is Koh Samui hot in August?
Yes. In August, Koh Samui is hot: daytime highs average 30 °C and nights stay around 27 °C. On about 9 days the thermometer climbs to 30 °C or more.
Can you swim in Koh Samui in August?
Yes. In August the sea averages 29.4 °C – almost as warm as a bath.
Does it rain much in Koh Samui in August?
It rains often – on about 21 days, adding up to 124 mm.
Koh Samui month by month
The whole year in Koh SamuiAll destinations: Thailand
Climate averages 1996–2025, not a forecast. Data: Copernicus ERA5 / ERA5-Land via Open-Meteo.com (CC BY 4.0), NOAA OISST, GeoNames (CC BY 4.0)