Brentwood Weather in September

What's the weather like in Brentwood (New Hampshire) in September 2025?

The climate in Brentwood during September can be summarized as mild and a little damp.

September is in the fall / autumn in Brentwood and is typically the 4th warmest month of the year. Daytime maximum temperatures average around 23°C (73°F), whilst at night 10°C (50°F) is normal.

Brentwood weather averages (imperial / metric)
Daytime temperature 22.6°C 72.7°F
Nightly temperature 9.8°C 49.6°F
Average temperature 16.2°C 61.2°F
Daily sunshine 8.1 hrs
Avg rainfall 84 mm 3.3 ins
Rainy days 9 days
Sea temperature 17.8°C 64.1°F
Humidity 75%
Windspeed 13kph 8 mph

On average September is the 5th driest month of the year in Brentwood with around 84mm 3.3 inches of rain making it a a little damp time to visit. This rainfall is typically spread over 9 days, although this may vary considerably.

On the flip side this corresponds to an average of 8.1 hours of sunshine per day.

September temperatures in Brentwood

Brentwood average temperature in September

September rainfall

Brentwood average rain in September

September hourly sunshine

Brentwood average rain in September

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 Brentwood in September 2025.

Other monthly averages

Best places to visit in September

UV index Best time to go?

Beta

Current (hourly) weather 15 day forecast

Brentwood weather stats

Brentwood weather statistics
Hottest month: July 27.6°C 81.7°F
Driest month: August 79mm 3.1ins
Sunniest month: July 10.1hrs
Coldest month: January 0.5°C 32.9°F
Wettest month: November 117mm 4.6ins
Map showing location of Brentwood (42.9787, -71.07284) Brentwood map pin © Google

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