The climate in Chepstow during September can be summarized as mild and reasonably dry.
September is in the fall / autumn in Chepstow and is typically the 4th warmest month of the year. Daytime maximum temperatures average around 18°C (64°F), whilst at night 10°C (50°F) is normal.
| Daytime temperature | 18°C 64.4°F |
|---|---|
| Nightly temperature | 9.8°C 49.6°F |
| Average temperature | 13.9°C 57°F |
| Daily sunshine | 5 hrs |
| Avg rainfall | 78 mm 3.1 ins |
| Rainy days | 14 days |
| Sea temperature | 16.2°C 61.2°F |
| Humidity | 86% |
| Windspeed | 14.4kph 9 mph |
On average September is the 5th wettest month of the year in Chepstow with around 78mm 3.1 inches of rain making it a reasonably dry time to visit. This rainfall is typically spread over 14 days, although this may vary considerably.
On the flip side this corresponds to an average of 5 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 Chepstow in September 2025.
Best places to visit in September
| Hottest month: | July | 20.8°C 69.4°F |
|---|---|---|
| Driest month: | July | 56mm 2.2ins |
| Sunniest month: | June | 7.2hrs |
| Coldest month: | January | 7°C 44.6°F |
| Wettest month: | December | 97mm 3.8ins |