The climate in Wiang Chai during September can be summarized as hot, humid and very wet.
September is in the fall / autumn in Wiang Chai and is typically the 6th warmest month of the year. Daytime maximum temperatures average around a steamy 31°C (87°F), whilst at night 22°C (72°F) is normal.
| Daytime temperature | 30.8°C 87.4°F | 
|---|---|
| Nightly temperature | 22.2°C 72°F | 
| Average temperature | 26.5°C 79.7°F | 
| Daily sunshine | 6 hrs | 
| Avg rainfall | 256 mm 10.1 ins | 
| Rainy days | 18 days | 
| Sea temperature | 29.1°C 84.3°F | 
| Humidity | 84% | 
| Windspeed | 2.9kph 2 mph | 
On average September is the 3rd wettest month of the year in Wiang Chai with around 256mm 10.1 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.
				
						
						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 Wiang Chai in September 2025.
Best places to visit in September
| Hottest month: | May | 33.1°C 91.6°F | 
|---|---|---|
| Driest month: | February | 8mm 0.3ins | 
| Sunniest month: | February | 9.7hrs | 
| Coldest month: | December | 26.2°C 79.2°F | 
| Wettest month: | August | 393mm 15.5ins |