Weather in Ko Samui in August 2025
Average weather
Average temperature in Ko Samui in August
The temperature in August is +27°C on average, with a range between a maximum of +29°C during the day and a minimum of +24°C at night.
The average maximum temperature goes up 20% by the end of the month, compared with the beginning of the month, from +27°C to +28°C.
Is Ko Samui warm or cold in August?
Ko Samui is typically warm in August.
Maximum temperatures go up compared to the previous month from +27°C to +27°C. The minimum temperature also goes up from +25°C to +25°C.
It’s generally warm, but pack a long-sleeve shirt for evenings.
Take a look at how August is compared to other months in Ko Samui:
Water temperature in Ko Samui in August
Water in Ko Samui in August is Very warm. It varies from +28°C to +30°C, with an average of +29°C. Note that the air temperature is lower than the water temperature, averaging around +27°C.
In August, water temperatures are average relative to the rest of the year:
Can you swim in Ko Samui in August?
Climate in Ko Samui in August
| July | August | September | ||||
|---|---|---|---|---|---|---|
| Avg. temperature | ||||||
| +27°C | +27°C | +27°C | ||||
| Min. temperature | ||||||
| +21°C | +20°C | +21°C | ||||
| Max. temperature | ||||||
| +33°C | +33°C | +32°C | ||||
| Rainfall | ||||||
| 82 mm | 85 mm | 142 mm | ||||
| Wind | ||||||
| 3 m/s | 3 m/s | 3 m/s | ||||
| Avg. water temperature | ||||||
| +30°C | +29°C | +29°C | ||||
| Humidity | ||||||
| 77% | 78% | 79% | ||||
| Air pressure | ||||||
| 1008 HPa | 1008 HPa | 1008 HPa | ||||
| Sunny days | ||||||
| 0 | 0 | 0 | ||||
| Cloudy days | ||||||
| 3 | 4 | 2 | ||||
| Rainy days | ||||||
| 17 | 18 | 17 | ||||
| Snowy days | ||||||
| 0 | 0 | 0 | ||||
August weather is still as ok as in July. The temperature levels stay the same in the area of +27°C for average maximum temperature during the day. Prepare for more rain. Average rainfall goes from 82 mm to 85 mm. Humidity rises from 77% to 78%. The average wind speed doesn’t change much during August, staying around 3 m/s. The amount of sunny days stay about the same, averaging 0 sunny days during the month.
September brings much the same weather, it remains ok.
Wind
The average wind speed is 4 m/s getting up to 5 m/s which is a light breeze; barely moving the tree leaves.
The average wind speed in Ko Samui is gradually increasing during August, going from 4 m/s to 5 m/s over the course of the month.
Rain
How was the weather last August in Ko Samui?
Climate Change over Years
The climate in Ko Samui in August has not changed much over the last 43 years.
The average temperature was the lowest in 1986 (+26°C) and the highest in 2012 (+28°C). The driest year was 1997 with only 927 mm of rainfall, and the wettest year was 1999 with 1981 mm.
FAQ
Is August a good time to visit Ko Samui?
Can you sunbathe in Ko Samui in August?
Can you swim in Ko Samui in August?
Is Ko Samui rainy in August?
Is it sunny in Ko Samui in August?
Other cities in Thailand
Monthly weather in Ko Samui
Source of the data
For this page, we’ve looked at the typical weather in Ko Samui, based on historical hourly weather data from January 1, 1979, to December 31, 2023.
For past dates, we show actual recorded data at the location at that time. Forecasts are based on recorded weather during that day of the year, averaged over the total years for which we have records (unless stated otherwise). The daily temperature is the highest recorded temperature in the shadow during that day.