Weather in September
September brings a changing wind to Cape Cod National Seashore as summer cools off and autumn approaches. The month's sea temperatures retreat slightly to an average of 64.3°F (17.9°C). Daylight hours continue to shrink, dropping to nearly half of July's length. Abutting August's summer and October's autumn, September is a transition that signals the end of warm days.
Note: Most people do not enjoy swimming in water that is 64.2°F (17.9°C). Breathing becomes increasingly challenging as the water temperature dips under 69.8°F (21°C).
On the first day of the month, sunrise is at 6:06 am and sunset at 7:13 pm. On the last day of September, sunrise is at 6:36 am and sunset at 6:22 pm EDT.
Ocean temperature
In Cape Cod National Seashore, the average seawater temperature in September is 64.2°F (17.9°C).Note: Most people do not enjoy swimming in water that is 64.2°F (17.9°C). Breathing becomes increasingly challenging as the water temperature dips under 69.8°F (21°C).
Daylight
In September, the average length of the day is 12h and 28min.On the first day of the month, sunrise is at 6:06 am and sunset at 7:13 pm. On the last day of September, sunrise is at 6:36 am and sunset at 6:22 pm EDT.
Updated: Jun 4, 2024
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
What is the ocean temperature in September?
In Cape Cod National Seashore, the average seawater temperature in September is 64.2°F (17.9°C). For most, swimming in 64.2°F (17.9°C) is not an enjoyable activity. Furthermore, controlling your breathing becomes progressively more difficult as the water temperature decreases from 69.8°F (21°C) to 59°F (15°C).
What is the average length of the day in September?
In Cape Cod National Seashore, the average day length in September is 12h and 28min.
When is the sunrise / sunset in September?
On the first day of September, sunrise is at 6:06 am and sunset at 7:13 pm. On the last day of the month, sunrise is at 6:36 am and sunset at 6:22 pm EDT.
Average sea temperature in September
Cape Cod National Seashore, MA
- Average sea temperature in September: 64.3°F
The best month for swimming (with the highest average sea temperature) is August (67.5°F).
The coldest month (with the lowest average sea temperature) is March (39°F).
Average daylight in September
Cape Cod National Seashore, MA
- Average daylight in September: 12h and 3min
The month with the longest days is June (Average daylight: 15h and 12min).
The month with the shortest days is December (Average daylight: 9h and 12min).
Cape Cod National Seashore, Massachusetts, USA
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