Porsgrunn Weather in September
What's the weather like in Porsgrunn (Telemark county) in September 2025?
The climate in Porsgrunn during September can be summarized as mild and damp.
September is in the fall / autumn in Porsgrunn and is typically the 4th warmest month of the year. Daytime maximum temperatures average around a cool 14°C (57°F), whilst at night 8°C (45°F) is normal.
| Daytime temperature | 14°C 57.1°F |
|---|---|
| Nightly temperature | 7.5°C 45.4°F |
| Average temperature | 10.7°C 51.3°F |
| Daily sunshine | 4.9 hrs |
| Avg rainfall | 120 mm 4.7 ins |
| Rainy days | 16 days |
| Sea temperature | 15.1°C 59.2°F |
| Humidity | 79% |
| Windspeed | 19.1kph 12 mph |
On average September is the 2nd wettest month of the year in Porsgrunn with around 120mm 4.7 inches of rain making it a damp time to visit. This rainfall is typically spread over 16 days, although this may vary considerably.
On the flip side this corresponds to an average of 4.9 hours of sunshine per day.
September temperatures in Porsgrunn
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 Porsgrunn in September 2025.
Other monthly averages
Best places to visit in September
Porsgrunn weather stats
| Hottest month: | July | 19.7°C 67.5°F |
|---|---|---|
| Driest month: | April | 52mm 2ins |
| Sunniest month: | June | 9.4hrs |
| Coldest month: | January | -2.3°C 27.9°F |
| Wettest month: | October | 136mm 5.4ins |
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