This post is an overview of the Boston weather in September, including average temperatures, chances of rain and sunshine, what to wear, and things to do.
As your tour guide and a former meteorologist, I provide practical weather information to help you plan your visit and know what to expect during your time in Boston.
September is one of my favorite months for exploring Boston. The month starts out feeling more like summer, while cooler fall weather gradually arrives as September progresses.
Let's take a look!
Boston Weather in September at a Glance
- Average high: Mid-70s F (24-25 C) early in the month, falling into the upper 60s F (19-20 C) by the end
- Average low: Lower 60s F (16-17 C) early in the month, falling into the mid-50s F (11-12 C) by the end
- Sunny or partly sunny days: About 20 days
- Rain: About 8-9 days with measurable rainfall
- Heavy rain: About 2 days
- Daylight: More than 13 hours early in the month, decreasing to just under 12 hours by the end
- Snow: Extremely unlikely
In This Article
What Is the Temperature Like in Boston in September?
September usually starts out warm in Boston, but temperatures gradually become cooler as the month progresses.
Early in September, daytime high temperatures tend to be in the mid to upper 70s F (about 24-25 C).
By the end of the month, afternoon temperatures are more likely to be in the mid to upper 60s F (19-20 C).
A few of the warmer afternoons early in September can reach into the 80s F (about 27-30 C). Temperatures reaching 90 F (32 C) or higher are uncommon.
The record high temperature recorded in Boston during September was 100 F (37.8 C).
Boston Temperatures in September
Late night and early morning temperatures also become cooler during September.
Early in the month, overnight lows tend to be in the lower 60s F (16-17 C). By the end of September, lows are more likely to be in the low to mid-50s F (11-12 C).
A few of the colder mornings toward the end of the month can dip into the mid-40s F (6-7 C).
The record low temperature in Boston during September was 38 F (3.3 C).
In short, September is one of the best months of the year to take a walking tour of Boston.
How Much Sun, Rain and Snow Does Boston Get in September?
September is generally a pleasant month for exploring Boston outdoors.
About 20 days during the month are either sunny or at least partly sunny.
Measurable rainfall occurs on about 8-9 days, although heavy rainfall of 0.5 inches (12.7 mm) or more is expected on only about 2 days.
Daylight in Boston in September
You can expect just over 13 hours of daylight early in September.
Daylight gradually decreases throughout the month, reaching just under 12 hours by the end of September.
This still gives you plenty of time to explore Boston during the day, particularly if you plan your outdoor activities earlier in your visit.
Snow is extremely unlikely in Boston during September.
What to Wear in Boston in September
September is a transition month in Boston, so I recommend packing clothing that can be layered.
Early September can still feel like summer, especially during the afternoon. Later in the month, mornings and evenings can feel distinctly more like fall.
I recommend bringing:
- Lightweight shirts and pants
- A sweater or sweatshirt
- A light jacket or windbreaker
- Comfortable walking shoes
- An umbrella or lightweight rain jacket
If you're visiting during the second half of September, you'll be glad to have a sweater or light jacket for cooler mornings and evenings.
And don't forget good walking shoes. Boston is a city best explored on foot!
What to Do in Boston in September
September's comfortable temperatures make it an excellent month for sightseeing, walking tours, outdoor activities, and exploring Boston's historic neighborhoods.
For a complete list of seasonal events and activities, see our guide to Things to Do in Boston in September.
You may also want to read our guide to the Best Things to Do in Boston for activities you can enjoy any time of year.
Some of the fun things to do in Boston in September include:
- Attend a Concert
- Watch a Musical
- Attend a Major Sporting Event
- Attend the Boston Local Food Festival
- Take a Walking Tour
- Cruise the Charles River
If you're planning to visit several of Boston's top attractions, you may also want to compare the cost of individual admission with a Boston tourist attraction pass. Depending on your itinerary, you could save money by purchasing a pass.
Seasonal Weather Outlook for Boston
September to November 2026 Boston
The seasonal outlook can provide a general indication of what to expect during the fall, although it cannot predict the weather for a specific day or individual trip.
For the latest information, check the NOAA Climate Prediction Center's seasonal outlooks.
Related Boston Weather Guides
Fred Pickhardt
Ocean Weather Services
