September · United States
Best time to visit Boston in September Weather, crowds & prices
Weather in Boston in September
Average temperature 18°C, 109 mm of rain, about 13 days with 6+ hours of sunshine and 77% humidity — based on the five most recent complete years of ERA5 data (2021–2025).
September score
7.2/10
Ranked #4 of 12 months
- Avg temp
- 18°C
- Rainfall
- 109 mm
- Humidity
- 77%
- Days with 6h+ sun
- 13
- Crowd Density
- Moderate Crowds
- Average Expenses
- $$ · Moderate Cost ($$)
September in Boston scores 7.2/10 for sightseeing and cultural travel - an above-average month (#4 of 12). Expect around 18°C, 109 mm of rain, and roughly 13 days with 6+ hours of sunshine this month.
Freedom Trail bricks, harbor ferries, and campus greens feel finest May through September.
September in Boston: strong conditions, 4th of 12
Temperatures hover around 18°C (65°F) — the kind of month where neither heat nor cold forces the schedule.
109 mm of rain signals a properly wet month, with only about 13 days with 6+ hours of sunshine to count on — build indoor options into the schedule.
That is 7.2/10 on the same scale — 4th of 12 months, versus 8.2/10 for the best month here.
Pack layers you can shed by midday plus one warm layer for the evening, a proper rain shell rather than an umbrella.
Budget for mid-season pricing, and crowds are moderate.
Frequently asked
- What is the weather like in Boston in September?
- In September, Boston averages 18°C, 109 mm of rain, and about 13 days with 6+ hours of sunshine. Its climate-comfort score is 7.2/10.
- Is September a good time to visit Boston?
- September earns a 7.2/10 climate-comfort score. Use the year-round chart to weigh the weather against your budget and crowd preferences.
- How much does it rain in Boston in September?
- Expect about 109 mm of rain in September. Average humidity is 77% and there are about 13 days with 6+ hours of sunshine.
Curated in Boston
Tickets & experiences
Things to do in Boston
Boston, United States. Live activities and tours from GetYourGuide, matched to this destination.