Monthly climate guide
Boston weather in September
Expect warm weather in Boston in September: afternoons reach about 24°C (75°F), while nights drop to around 13°C (56°F). Around 91 mm of rain falls over the month (wet), and skies are a mix of sun and cloud. Daytime highs are 4°C cooler than August and 7°C warmer than October.
What stands out in September
- It cools down fast from here: October is about 7°C cooler.
- Only 2 months are warmer in Boston than September.
- Just 80 km apart, but Boston runs about 5°C warmer than Provincetown this month.
- Seasonally, September counts as early autumn in Boston.
Avg high
24°C
75°F
Avg low
13°C
56°F
Rainfall
91 mm
wet
Humidity
74%
relative
Sky
53%
cloud · a mix of sun and cloud
Boston weather by month
Show the monthly averages as a table
| Month | Avg high | Avg low | Rain | Humidity | Cloud cover |
|---|---|---|---|---|---|
| January | 1°C / 34°F | -7°C / 19°F | 84 mm | 87% | 62% |
| February | 2°C / 35°F | -7°C / 19°F | 92 mm | 88% | 63% |
| March | 6°C / 43°F | -3°C / 26°F | 86 mm | 82% | 61% |
| April | 13°C / 55°F | 2°C / 36°F | 108 mm | 79% | 63% |
| May | 19°C / 66°F | 9°C / 47°F | 77 mm | 79% | 65% |
| June | 24°C / 74°F | 14°C / 56°F | 116 mm | 78% | 60% |
| July | 28°C / 83°F | 18°C / 64°F | 87 mm | 75% | 54% |
| August | 28°C / 82°F | 17°C / 63°F | 96 mm | 72% | 51% |
| September | 24°C / 75°F | 13°C / 56°F | 91 mm | 74% | 53% |
| October | 17°C / 63°F | 8°C / 46°F | 125 mm | 79% | 61% |
| November | 10°C / 49°F | 1°C / 34°F | 97 mm | 81% | 57% |
| December | 4°C / 40°F | -3°C / 27°F | 122 mm | 87% | 66% |
What to pack for September
- T-shirts plus a light layer for the evening
- Comfortable trainers or sandals for long walks
- A compact umbrella or packable rain jacket
- Water-resistant shoes
Is September a good time to visit Boston?
Compare the months in the chart above to find your ideal window.
Best time to visit Boston →Other United States cities in September
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Boston weather in September. WeatherCompare, 2026 (NASA POWER / ERA5, 2011–2020 monthly averages). https://weathercompare.eu/weather/usa/boston/september
<a href="https://weathercompare.eu/weather/usa/boston/september">Boston weather in September</a> (WeatherCompare)
<iframe src="https://weathercompare.eu/embed/usa/boston" width="300" height="160" style="border:0;border-radius:12px" loading="lazy" title="Boston weather in September"></iframe> <p style="font-size:12px"><a href="https://weathercompare.eu/weather/usa/boston/september">Boston weather in September</a> – WeatherCompare</p>
Boston in September: quick answers
Is September a good time to visit Boston?
Yes. September is one of the best months for Boston, with highs around 24°C and about 91 mm of rain.
How warm is Boston in September?
Average highs are about 24°C (75°F) and average lows about 13°C (56°F), based on 10 years of daily data.
Does it rain a lot in Boston in September?
Boston typically gets around 91 mm of rain in September — wet.
Figures are long-term averages for the area around Boston (NASA POWER / ERA5, 2011–2020), not a forecast for a specific year. For upcoming days, see the live multi-source forecast.