The climate in Isernia during September can be summarized as mild and reasonably dry.
September is in the fall / autumn in Isernia and is typically the 4th warmest month of the year. Daytime maximum temperatures average around a comfortable 22°C (72°F), whilst at night 14°C (57°F) is normal.
Daytime temperature | 22.1°C 71.8°F |
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Nightly temperature | 13.7°C 56.7°F |
Average temperature | 17.9°C 64.2°F |
Daily sunshine | 7.8 hrs |
Avg rainfall | 67 mm 2.6 ins |
Rainy days | 8 days |
Sea temperature | 24°C 75.2°F |
Humidity | 69% |
Windspeed | 9.4kph 6 mph |
On average September is the 5th wettest month of the year in Isernia with around 67mm 2.6 inches of rain making it a reasonably dry time to visit. This rainfall is typically spread over 8 days, although this may vary considerably.
On the flip side this corresponds to an average of 7.8 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 Isernia in September 2025.
Best places to visit in September
Hottest month: | July | 25.6°C 78.1°F |
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Driest month: | July | 39mm 1.5ins |
Sunniest month: | August | 9.3hrs |
Coldest month: | January | 6.9°C 44.4°F |
Wettest month: | November | 105mm 4.1ins |