Boston weather in September 2025

Expect 23°C daytime maximum temperatures in the shade with on average 8 hours of sunshine per day in Boston in September. Check more long-term weather averages for Boston in September before you book your next holiday to Massachusetts in 2025/2026.

  • 23°C maximum daytime temperature in September in Boston23
    23°C max day temperature
  • 8 hours of sunshine per day
  • 8 days with some rainfall in September in Boston8
    8 days with some rainfall
  • 12°C minimum night-time temperature in September in Boston12
    12°C min night temperature
  • 12 hours of daylight per day in September in Boston12
    12 hours of daylight per day
  • No heat & humidity in September in Boston0
    No heat & humidity
  • 82 mm monthly rainfall in September in Boston82
    82 mm of monthly rainfall
  • UV (maximum) index 6 (High) in September in Boston6
    6 (High) UV index
  • 16°C sea temperature in September in Boston16
    16°C sea temperature

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The September weather guide for Massachusetts (Boston) shows long term weather averages processed from data supplied by CRU (University of East Anglia), the Met Office & the Netherlands Meteorological Institute. Find out more about our data sources.

Metric (°C / mm)  |  Imperial (°F / inches)

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More about the USA

How hot is it in Boston in September?

Daytime temperatures usually reach 23°C in Boston in September, falling to 12°C at night.

How sunny is it in Boston in September?

There are normally 8 hours of bright sunshine each day in Boston in September - that's 61% of daylight hours.

How warm is the sea around Boston in September?

The average sea temperature around Boston in September is 16°C.

Does it rain in Boston in September?

There are usually 8 days with some rain in Boston in September and the average monthly rainfall is 82mm.

What is the chance of a hurricane in Boston in September?

On average less than 1 day in September in Boston is likely to be affected by the passage of one or more tropical storms.

Boston September sunrise & sunset times

Browse the sunrise and sunset times for Boston in September 2025. Select a month to view Boston sunrise and sunset times for the next 12 months.

JanFebMarAprMayJunJulAugSepOctNovDec

Date Sunrise times Sunset times
Monday, 1st September 2025 05:10 18:18
Monday, 15th September 2025 05:24 17:53
Tuesday, 30th September 2025 05:41 17:27

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