Boston, MA weather in September
Boston is mild in September, with some rain: highs average 73°F and nights drop to about 58°F. Rain falls on about 9 days. A good month for most outdoor plans.
- Normal high
- 73°F
- Normal low
- 58°F
- Wet days
- 9
- 3.6 in total
- Muggy days
- 4
- dew point 65°F+
How September changes from start to finish
| September 1 | September 30 | |
|---|---|---|
| Normal high | 78°F | 68°F |
| Normal low | 63°F | 53°F |
| Chance of a wet day | 28% | 32% |
| Sunrise / sunset | 6:09 am / 7:18 pm | 6:40 am / 6:28 pm |
| Daylight | 13.2 h | 11.8 h |
Chance of a wet day: average for the first and last 7 days of the month. Times are local clock time (Eastern Time).
A typical September day
- 6 am61°Fdew point 55°F
- 9 am67°Fdew point 55°F
- Noon70°Fdew point 55°F
- 3 pm71°Fdew point 55°F
- 6 pm67°Fdew point 55°F
- 9 pm64°Fdew point 55°F
NOAA hourly normals (local standard time) from Boston Logan Intl Airport (3 mi away); average wind 10 mph; clear or few clouds in 32% of daytime hours, mostly cloudy or overcast in 48%.
What kind of days to expect
- Comfortable dayshigh 65-80°F and dew point under 60°F15 of 30
- Beach dayshigh 80-95°F, under 0.05 in of rain, afternoon wind under 15 mph4 of 30
- Hot dayshigh 90°F or more1 of 30
- Muggy daysdaily mean dew point 65°F or more4 of 30
- Wet daysat least 0.01 in of rain or melted snow9 of 30
- Notable rainat least 0.10 in6 of 30
- Freezing nightslow 32°F or below0 of 30
- Snow on the groundsnow depth 1 in or more0 of 30
Average days per September, counted from daily records for each year 1991-2020.
Rain in September
Normal precipitation is 3.6 in; a dry September brings about 1.9 in and a wet one about 4.5 in (25th and 75th percentiles). About 2 days bring half an inch or more, and about 1 an inch or more.
How September varies from year to year
- Warmest September, 1991-20202015: average high 77°F
- Coolest September1996: average high 70°F
- Wettest September1999: 9.9 in
- Driest September2014: 0.7 in
- Highest reading97°F (September 6, 2018)
- Lowest reading38°F (September 29, 2000)
From the station's daily records with NOAA quality flags removed; most recent date shown when a reading repeats.
September compared with August and October
| August | September | October | |
|---|---|---|---|
| Normal high | 80°F | 73°F | 62°F |
| Normal low | 65°F | 58°F | 48°F |
| Wet days | 9 | 9 | 11 |
| Comfortable days | 8 | 15 | 10 |
| Daylight | 13.8 h | 12.5 h | 11.1 h |
Highs change by -7°F from August and -11°F into October.
Nearby alternatives in September
- Warmer: Paterson, NJ189 mi · high 78°F · 9 wet days
- Cooler: Lake Placid, NY198 mi · high 66°F · 12 wet days
How Boston ranks in September
- Normal high315th warmest of 378 cities; 7th of 9 in Massachusetts
- Wet days246th driest of 378
- Comfortable days72nd most of 342
What to pack for Boston in September
- A rain jacket or umbrella – rain on about 9 days
Heating and cooling
September has 71 heating degree days and 91 cooling degree days (base 65°F), 3% of the year's total heating and cooling demand.
Questions
How hot is Boston in September?
The normal high is 73°F and the normal low is 58°F. From 1991 to 2020 the hottest September reading was 97°F (most recently on September 6, 2018).
Does it rain a lot in Boston in September?
About 9 days in September have at least 0.01 in of precipitation, and the normal total is 3.6 in. The wettest September in 1991-2020 was in 1999 (9.9 in); the driest was in 2014 (0.7 in).
Is September a good time to visit Boston?
September ranks 3rd of 12 months on our comfort score for Boston (68 out of 100). It has about 15 comfortable days and about 1 day at 90°F or hotter. The best months are May, June and September.
Where the numbers come from
- Temperature, rain, snowfall, frost dates, humidity and wind by hour and cloud cover: Boston Logan Intl Airport (USW00014739), 2.5 mi E of the city center, 12 ft . NOAA normals and daily records, 1991-2020.
- Snow depth: Hingham (USC00193624), 12 mi SE of the city center, 35 ft . NOAA normals and daily records, 1991-2020.
- Daily humidity and wind: Gen E L Logan International Airport (725090-14739), 2.5 mi E of the city center, 11 ft . Hourly observations, 1991-2020.