The temperatures in Hertfordshire in September are usually low and can range between 12°C and 20°C.
You can expect about 3 to 8 days of rain in Hertfordshire during the month of September. It’s a good idea to bring along your umbrella so that you don’t get caught in poor weather.
Our weather forecast can give you a great sense of what weather to expect in Hertfordshire in September 2025.
If you’re planning to visit Hertfordshire in the near future, we highly recommend that you review the 14 day weather forecast for Hertfordshire before you arrive.