Boston weather in September
Boston in September averages 19°C (66°F), 90 mm of rain and 7.1 hours of sun a day.
Of the twelve months in Boston, September is the fourth warmest, the sixth driest and the fifth sunniest.
- Average temp
- 19°C (66°F)
15–23°C · 58–73°F
- Rainfall
- 90 mm
Showers likely
- Sunshine
- 7.1 h
hours per day
- Wind
- 16 km/h
What is Boston like in September?
Daytime
Days are mild.
Rain
Some rain is likely; pack for showers.
Evening
Evenings are cooler. A layer helps after sunset.
What should I pack for Boston in September?
A light rain jacket
About 90 mm falls this month — showers rather than washouts.
A layer for the evening
Evenings cool off noticeably once the sun is down.
September compared with August and October
September in Boston is 4°C cooler than August and 10 mm wetter than it, which averages 23°C (73°F).
September in Boston is 6°C warmer than October and 11 mm drier than it, which averages 13°C (55°F).
Daylight in Boston in September
On 15 September the sun is up for 12 hours 28 minutes in Boston, rising about 06:24 and setting about 18:52 local time.
September ends 1 hour 21 minutes shorter than it begins, so the last week of the month is a different length of day from the first.
That is 2 hours 48 minutes short of June, the longest-lit month here.
Where to stay in Boston
Dates are a starting point for September.
Travel guides for Boston
What to read before you book.
Boston weather by month
TemperatureRainfall
How September compares with the rest of the year
September is highlighted. Every other month links to its own page.
| Month | Average | Rainfall |
|---|---|---|
| January | -1°C / 30°F | 84 mm |
| February | 0°C / 32°F | 79 mm |
| March | 4°C / 38°F | 105 mm |
| April | 9°C / 49°F | 91 mm |
| May | 15°C / 59°F | 83 mm |
| June | 20°C / 68°F | 99 mm |
| July | 24°C / 74°F | 82 mm |
| August | 23°C / 73°F | 80 mm |
| September | 19°C / 66°F | 90 mm |
| October | 13°C / 55°F | 101 mm |
| November | 7°C / 45°F | 93 mm |
| December | 2°C / 36°F | 107 mm |
Check another month
This is the month you are reading. Change either side to look at another.
FAQs about Boston in September
September climate averages for Boston, 1991–2020.
Boston averages 19°C (66°F) in September, ranging from about 15°C (58°F) at night to 23°C (73°F) in the afternoon. That is a 1991–2020 average, so an individual week can run either side of it.
Some. About 90 mm falls across September, enough to need a light jacket but not enough to reshape a trip.
Yes. September averages 19°C (66°F) against 13°C (55°F) in October — 6°C warmer.
September is 4°C cooler than August, and 10 mm wetter.
Yes. September falls inside the most comfortable stretch of the year here, May to October, on temperature and rainfall together.
About 7.1 hours of sun a day on the 1991–2020 average.
This page does not show today's weather. It is a 1991–2020 climate normal from Meteostat — a long-run average of what September is usually like, which is what you want when booking months ahead. For today or the coming week, check a live forecast.
About 12 hours 28 minutes of daylight in mid-September, against 15 hours 16 minutes in June and 9 hours 6 minutes in December.
On 15 September, sunrise is about 06:24 and sunset about 18:52 local time. Both shift across the month — the month ends 1 hour 21 minutes shorter than it starts.
