San Sai Weather in September
What's the weather like in San Sai (Chiang Mai) in September 2025?
The climate in San Sai during September can be summarized as hot, humid and very wet.
September is in the fall / autumn in San Sai and is typically the 6th warmest month of the year. Daytime maximum temperatures average around a steamy 31°C (88°F), whilst at night 23°C (72°F) is normal.
| Daytime temperature | 31°C 87.7°F |
|---|---|
| Nightly temperature | 22.5°C 72.4°F |
| Average temperature | 26.7°C 80.1°F |
| Daily sunshine | 6 hrs |
| Avg rainfall | 228 mm 9 ins |
| Rainy days | 18 days |
| Sea temperature | 29°C 84.1°F |
| Humidity | 82% |
| Windspeed | 2.9kph 2 mph |
On average September is the 2nd wettest month of the year in San Sai with around 228mm 9 inches of rain making it a very wet time to visit. This rainfall is typically spread over 18 days, although this may vary considerably.
On the flip side this corresponds to an average of 6 hours of sunshine per day.
September temperatures in San Sai
September rainfall
September hourly sunshine
The data used in these monthly averages covers a period of over 100 years right up until last year. As such they are a valid prediction of what to expect for the weather in San Sai in September 2025.
Other monthly averages
Best places to visit in September
San Sai weather stats
| Hottest month: | April | 35.6°C 96.1°F |
|---|---|---|
| Driest month: | February | 6mm 0.2ins |
| Sunniest month: | February | 10.4hrs |
| Coldest month: | January | 28.4°C 83.1°F |
| Wettest month: | August | 246mm 9.7ins |
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