Boston Weather in September
With daytime temperatures of 24°C (75°F) and nighttime lows of 15°C (59°F), September in Boston brings high temperatures during the day. It is also the driest month of the year, with minimal rainfall.
Rainfall in Boston in September
Enjoy minimal rain interruptions this month. It's an excellent time for outdoor plans, from sports to festivals. The climate data from previous years indicates about 9 days of rain, averaging 79 mm (3.1 in) for the month. When it rains this month, it tends to come down fairly heavily. Showers can be substantial even if they don't last all day.
Temperature in Boston in September
Weather in Boston is at its perfect in September. Highs reach 24°C (75°F), while nights settle around 15°C (59°F). This kind of day-to-night contrast is typical for this time of year. With overnight lows of 15°C (59°F), evenings can feel noticeably cooler than the daytime. An extra layer is a good idea, though the cool air makes for a good night's sleep.
Sunshine in Boston in September
With approximately 238 hours of sunshine, the days are filled with clear skies. It makes it a perfect month for being outside.
Wind Speed in Boston in September
Wind speeds average 5 m/s (10 knots) during September. At this speed, gentle to moderate breezes make small trees sway and the wind creates whitecaps on water bodies. Daily variations range from moderate winds to stronger breezes, creating excellent conditions for sailing, kite flying and wind sports.
Average water temperature in September
With water at 18°C (64°F), swimming is comfortable for most people. It feels refreshing rather than cold, though it depends a bit on personal preference.Our weather planner can help you find worldwide destinations with pleasant weather during this period. August and September typically offer the best weather for Boston.
Check the conditions for any month of the year.
For a detailed overview over the year and the best time to visit the United States of America, check out our Boston's climate page.
Boston Temperature in September
Min Temperature
15°C (59°F)
Max Temperature
24°C (75°F)
Water Temperature
18°C (64°F)
Chance of Rain
30%
Precipitation
79 mm (3.1 in)
Rainy days
9 days
Humidity
69%
Windspeed
5 m/s (10 knots)
Sunshine
238 hours
Percentage Sunshine
63%
Daily Historical Temperatures
50-year average (1976-2025)
Based on our historical records, temperatures in Boston typically drop from around 25°C (77°F) at the start of September to approximately 20°C (68°F) by the end. Nights are pleasant, with lows typically ranging from 12°C (54°F) to 17°C (63°F).
Average temperatures in September
Daily Historical Precipitation
50-year average (1976-2025)
Average daily rainfall for each day of the month based on long-term records.
Average precipitation in September
Historical weather for Boston in September
Browse day-by-day weather records for Boston spanning 51 years. Select any month and year to see actual temperatures, rainfall, and conditions recorded on each day.
Boston historical weather extremes in September
The extremes listed below come from historical weather data collected in Boston from 1976 through 2025.
- The warmest day in September was on September 11, 1983, with a maximum of 37°C (99°F).
- On September 29, 2000, Boston saw its coldest September day with temperatures maxing out at 11°C (52°F).
- Nighttime temperatures dropped to 4°C (39°F) on September 29, 2000, marking the coldest September night on record.
Best Places in the United States of America in September
Find out more about the weather in the United States of America and which places have the best travel conditions in this month. See all of the United States of America in September →
perfect weather
pleasant
tolerable
unpleasant
poor
What to Wear in Boston in September
Pleasant temperatures in September mean you can pack light but flexibel pieces. Think cotton t-shirts, comfortable walking shorts, and one warmer layer for evenings. A light sweater or denim jacket works well. Rain gear is recommended, you can expect wet weather on multiple days. With water temperatures around 18°C (64°F), the water is quite cold for swimming. You can skip the swimwear unless you're particularly tough. And with plenty of sunshine hours, don’t forget sunglasses, sunscreen, and maybe a sun hat.What To Do in Boston in September
We rated the following activities from 1 (least suitable) to 10 (best) to do.
Check the conditions for any month of the year.
For a detailed overview over the year and the best time to visit the United States of America, check out our Boston's climate page.
Temperature Rainfall Sunshine Humidity Wind Speed Water Temp
See the full Boston climate overview or explore weather in the United States of America.
