Castine Weather in September

What's the weather like in Castine (Maine) in September 2025?

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

September is in the fall / autumn in Castine and is typically the 4th warmest month of the year. Daytime maximum temperatures average around 21°C (69°F), whilst at night 10°C (49°F) is normal.

Castine weather averages (imperial / metric)
Daytime temperature 20.5°C 68.9°F
Nightly temperature 9.5°C 49.1°F
Average temperature 15°C 59°F
Daily sunshine 7 hrs
Avg rainfall 97 mm 3.8 ins
Rainy days 10 days
Sea temperature 13.3°C 55.9°F
Humidity 79%
Windspeed 12.6kph 8 mph

On average September is the 4th wettest month of the year in Castine with around 97mm 3.8 inches of rain making it a a little damp time to visit. This rainfall is typically spread over 10 days, although this may vary considerably.

On the flip side this corresponds to an average of 7 hours of sunshine per day.

September temperatures in Castine

Castine average temperature in September

September rainfall

Castine average rain in September

September hourly sunshine

Castine 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 Castine 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

Castine weather stats

Castine weather statistics
Hottest month: July 25.8°C 78.4°F
Driest month: August 78mm 3.1ins
Sunniest month: August 8.1hrs
Coldest month: January -2°C 28.4°F
Wettest month: November 123mm 4.8ins
Map showing location of Castine (44.38785, -68.79975) Castine map pin © Google

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