Koesan Weather in September
What's the weather like in Koesan (North Chungcheong) in September 2025?
The climate in Koesan during September can be summarized as warm and wet.
September is in the fall / autumn in Koesan and is typically the 4th warmest month of the year. Daytime maximum temperatures average around 25°C (77°F), whilst at night 13°C (56°F) is normal.
| Daytime temperature | 24.8°C 76.6°F |
|---|---|
| Nightly temperature | 13.4°C 56.1°F |
| Average temperature | 19.1°C 66.4°F |
| Daily sunshine | 7.3 hrs |
| Avg rainfall | 136 mm 5.3 ins |
| Rainy days | 9 days |
| Sea temperature | 23.5°C 74.4°F |
| Humidity | 79% |
| Windspeed | 4kph 2 mph |
On average September is the 4th wettest month of the year in Koesan with around 136mm 5.3 inches of rain making it a wet time to visit. This rainfall is typically spread over 9 days, although this may vary considerably.
On the flip side this corresponds to an average of 7.3 hours of sunshine per day.
September temperatures in Koesan
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 Koesan in September 2025.
Other monthly averages
Best places to visit in September
Koesan weather stats
| Hottest month: | August | 29°C 84.2°F |
|---|---|---|
| Driest month: | December | 27mm 1.1ins |
| Sunniest month: | March | 7.7hrs |
| Coldest month: | January | 0.5°C 32.9°F |
| Wettest month: | July | 309mm 12.2ins |
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