Siilinjärvi Weather in September
What's the weather like in Siilinjärvi (Eastern Finland Province) in September 2025?
The climate in Siilinjärvi during September can be summarized as cool and reasonably dry.
September is in the fall / autumn in Siilinjärvi and is typically the 4th warmest month of the year. Daytime maximum temperatures average around a cool 12°C (54°F), whilst at night 6°C (43°F) is normal.
| Daytime temperature | 12.2°C 53.9°F |
|---|---|
| Nightly temperature | 6.1°C 42.9°F |
| Average temperature | 9.1°C 48.4°F |
| Daily sunshine | 4 hrs |
| Avg rainfall | 64 mm 2.5 ins |
| Rainy days | 17 days |
| Sea temperature | 11.5°C 52.7°F |
| Humidity | 84% |
| Windspeed | 12.6kph 8 mph |
On average September is the 3rd wettest month of the year in Siilinjärvi with around 64mm 2.5 inches of rain making it a reasonably dry time to visit. This rainfall is typically spread over 17 days, although this may vary considerably.
On the flip side this corresponds to an average of 4 hours of sunshine per day.
September temperatures in Siilinjärvi
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 Siilinjärvi in September 2025.
Other monthly averages
Best places to visit in September
Siilinjärvi weather stats
| Hottest month: | July | 20.9°C 69.6°F |
|---|---|---|
| Driest month: | February | 28mm 1.1ins |
| Sunniest month: | June | 0hrs |
| Coldest month: | January | -7.9°C 17.8°F |
| Wettest month: | August | 80mm 3.1ins |
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