South Yarmouth Weather in September

What's the weather like in South Yarmouth (Massachusetts) in September 2025?

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

September is in the fall / autumn in South Yarmouth and is typically the 4th warmest month of the year. Daytime maximum temperatures average around 21°C (70°F), whilst at night 13°C (56°F) is normal.

South Yarmouth weather averages (imperial / metric)
Daytime temperature 21.2°C 70.1°F
Nightly temperature 13.3°C 55.9°F
Average temperature 17.2°C 63°F
Daily sunshine 8.2 hrs
Avg rainfall 87 mm 3.4 ins
Rainy days 8 days
Sea temperature 18.4°C 65.2°F
Humidity 75%
Windspeed 15.1kph 9 mph

On average September is the 4th driest month of the year in South Yarmouth with around 87mm 3.4 inches of rain making it a a little damp 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 8.2 hours of sunshine per day.

September temperatures in South Yarmouth

South Yarmouth average temperature in September

September rainfall

South Yarmouth average rain in September

September hourly sunshine

South Yarmouth 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 South Yarmouth 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

South Yarmouth weather stats

South Yarmouth weather statistics
Hottest month: July 25.2°C 77.4°F
Driest month: July 68mm 2.7ins
Sunniest month: September 8.2hrs
Coldest month: January 2.4°C 36.3°F
Wettest month: November 116mm 4.6ins
Map showing location of South Yarmouth (41.66678, -70.18474) South Yarmouth map pin © Google

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