United States Boston Weather in September — Climate Guide
September in Boston is very-high
September is very-high for Boston.
September is the canonical sweet-spot month for visiting Boston — ideal weather (14-23°C / 57-73°F), summer tourism ending, fall foliage beginning, Boston Symphony Hall season starting.
Universities resume — Harvard + MIT + Boston University + Northeastern + Boston College students arrive in Cambridge + Allston/Brighton + Fenway. The college-tour-family departure surge ending. Cambridge buzzes with new students.
Travel score
Boston September Weather Stats
Avg High
23°C
Avg Low
14°C
Rainy Days
9
90mm total
Sunshine
9h
Daily avg
Humidity
65%
moderate
UV Index
7
High
Wind
12 km/h
Gusts 30
Sea Temp
19°C
swimming
Crowds
Very busy
At attractions
September Sunrise & Sunset
Air Quality
PM2.5
7 μg/m³
PM10
17 μg/m³
Status
good
Feels-Like Temperature & Wind
Feels like
Daytime
24°C
Nighttime
15°C
Humidity and wind affect how the actual temperature feels.
Wind
12 km/h
Max gust 30 km/h
Activities Recommended for September
September Travel Pros & Cons
Pros
- Ideal weather 14-23°C
- Summer crowds ending
- Boston Symphony Hall + Pops fall season starts
- Boston Calling Music Festival
- Fenway Park Red Sox playoff push
Cons
- University-arrival week chaos late August/early September
- Boston Calling Festival weekend hotel surge
- Fall pricing climbing late month
- Pre-foliage-peak demand
September Events & Festivals
- Labor Day weekend (1st Mon Sept)
- Harvard + MIT + Boston University fall semester begins
- Boston Calling Music Festival (Sep)
- Yom Kippur (varies)
- Boston Symphony Hall fall season begins
Boston in September — Full Picture
September is the canonical sweet-spot month for visiting Boston — ideal weather (14-23°C / 57-73°F), summer tourism ending, fall foliage beginning, Boston Symphony Hall season starting.
Universities resume — Harvard + MIT + Boston University + Northeastern + Boston College students arrive in Cambridge + Allston/Brighton + Fenway. The college-tour-family departure surge ending. Cambridge buzzes with new students.
Labor Day weekend (1st Monday September, US holiday) kicks off the post-summer transition. Cape Cod tourism ending — September Cape Cod is the locals' favorite shoulder season.
Boston Symphony Hall + Boston Pops fall season begins. Boston Calling Music Festival (varies September) at Allston/Harvard Athletic Complex — major indie/rock acts (Khruangbin, Hozier, Arctic Monkeys past headliners). Tickets $250-450 weekend pass.
Weather sweet spot — afternoon thunderstorms diminishing, humidity dropping, daylight still long (12h 30m by end of month). Fall foliage starting to color (peak mid-October).
The smart September move: target the second or third week (post-Labor Day, pre-fall-foliage surge) for the year's best weather-to-pricing combination on Boston.
What to Wear & What to Pack
Ideal early-fall — t-shirt + sweater + light jacket evening. Sunshine + comfortable 14-23°C. Universities resume + tourist families departing — sweet spot.
Packing Checklist
Seasonal Weather Overview
Spring (Mar·Apr·May)
14°C
4.3°C
11.7/mo
Summer (Jun·Jul·Aug)
26.7°C
17.3°C
9.7/mo
Autumn (Sep·Oct·Nov)
Current17°C
8.3°C
9.7/mo
Winter (Dec·Jan·Feb)
3.7°C
-4.7°C
11/mo
Boston Monthly Weather Comparison
| Month | High | Low | Rain | Sun | Humid | UV | Crowd | Price |
|---|---|---|---|---|---|---|---|---|
| 2° | -6° | 11d·90mm | 5h | 65% | 2 | Quiet | Low season | |
| 4° | -5° | 10d·80mm | 6h | 64% | 3 | Quiet | Low season | |
| 8° | -1° | 12d·95mm | 7h | 62% | 4 | Quiet | Low season | |
| 14° | 4° | 12d·95mm | 8h | 60% | 5 | Very busy | Peak | |
| May (Best) | 20° | 10° | 11d·90mm | 9h | 60% | 7 | Very busy | Peak |
| June (Best) | 25° | 15° | 11d·90mm | 10h | 64% | 9 | Busy | Peak |
| July (Best) | 28° | 19° | 9d·85mm | 11h | 67% | 10 | Very busy | Peak |
| August (Best) | 27° | 18° | 9d·90mm | 10h | 70% | 9 | Very busy | Peak |
| September (Best) | 23° | 14° | 9d·90mm | 9h | 65% | 7 | Very busy | Peak |
| October (Best) | 17° | 8° | 9d·95mm | 7h | 65% | 5 | Very busy | Peak |
| 11° | 3° | 11d·95mm | 5h | 65% | 3 | Busy | Peak | |
| 5° | -3° | 12d·100mm | 5h | 65% | 2 | Very busy | Peak |
View Other Months
Boston September Hotel Picks
Frequently Asked Questions
Is September a good time to visit Boston?
Boston in September is very-high. Tourist crowds are very busy and flight/hotel prices are peak.
What's the average temperature in Boston in September?
Boston September averages a high of 23°C and a low of 14°C.
Does it rain much in Boston in September?
Boston September averages 90mm of rainfall over about 9 rainy days.
What should I wear in Boston in September?
Ideal early-fall — t-shirt + sweater + light jacket evening. Sunshine + comfortable 14-23°C. Universities resume + tourist families departing — sweet spot.
What time are sunrise and sunset in Boston in September?
Boston September sunrise is 06:15 and sunset is 18:55, with 12h 40m of daylight.
What's the air quality like in Boston in September?
Boston September air quality (AQI) averages 28, rated Good. PM2.5 averages 7μg/m³.
What activities are recommended in Boston in September?
In September, Boston is great for Freedom Trail (ideal weather), Boston Calling Music Festival, Boston Symphony Hall fall opening.
Is September peak season in Boston?
Boston September crowds are very busy and prices are peak. Advance reservations are strongly recommended.
Best Months to Visit Boston
View Other Months
Why you can trust weather guide
Based in Chiang Mai for 8+ years, with 30+ countries visited across Southeast Asia, Japan, and Europe. Every detail in this guide is primary-source verified as of April 2026, with prices auto-refreshed via live exchange rate APIs. This isn't AI-generated boilerplate — it's written from the perspective of someone who has actually been there.