September weather forecastBoston, MA
September
Weather in September
As Boston steps into September, the city starts bidding farewell to summer and welcomes the fall. A shift in the weather pattern from August is noticeable, with high and low temperatures registering at 72.7°F (22.6°C) and 57.4°F (14.1°C) respectively. The change is greeted with a crisp in the air, signaling the arrival of the fall season. September also introduces the vibrant autumnal hues, with orange and red leaves adorning the cityscape.Temperature
In Boston, entering September brings a subtle temperature decrement, reducing from August's moderately hot 80.4°F (26.9°C) to an agreeable 72.7°F (22.6°C). The average low-temperature during September nights is a moderate 57.4°F (14.1°C).Humidity
The average relative humidity in September is 75%.Rainfall
September is the month with the least rainfall. Rain falls for 10 days and accumulates 1.26" (32mm) of precipitation.Snowfall
In Boston, snow does not fall in June through September.Ocean temperature
In Boston, in September, the average water temperature is 64.8°F (18.2°C).Note: For most, swimming in 64.8°F (18.2°C) is not a pleasant experience. As the temperature falls from 69.8°F (21°C) to 59°F (15°C), controlling one's breathing becomes more difficult.
Daylight
In Boston, the average length of the day in September is 12h and 28min.On the first day of September, sunrise is at 6:10 am and sunset at 7:17 pm. On the last day of the month, sunrise is at 6:40 am and sunset at 6:26 pm EDT.
Sunshine
The average sunshine in September is 8.4h.UV index
In Boston, the average daily maximum UV index in September is 4. A UV Index of 3 to 5 symbolizes a medium vulnerability from unprotected exposure to Sun's UV rays for the average person.Note: The maximum daily UV index of 4 in September interprets into the following recommendations:
Be cautious. Those with fair skin can be subjected to burns in fewer than 30 minutes. The solar radiation is most powerful near the mid-day, so the exposure to the direct Sun should be reduced accordingly. Equip yourself with UVA and UVB-filtering sunglasses on clear, sunny days.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in September
Boston, MA
- Average high temperature in September: 72.7°F
The warmest month (with the highest average high temperature) is July (81.7°F).
The month with the lowest average high temperature is January (34.2°F).
- Average low temperature in September: 57.4°F
The month with the highest average low temperature is July (64.9°F).
The coldest month (with the lowest average low temperature) is January (22.6°F).
Average pressure in September
Boston, MA
- Average pressure in September: 30.05"Hg
The month with the highest atmospheric pressure is November (30.06"Hg).
The month with the lowest atmospheric pressure is June (29.93"Hg).
Average wind speed in September
Boston, MA
- Average wind speed in September: 6.8mph
The windiest month (with the highest average wind speed) is January (9.9mph).
The calmest month (with the lowest average wind speed) is August (6.2mph).
Average humidity in September
Boston, MA
- Average humidity in September: 75%
The month with the highest relative humidity is February (77%).
The month with the lowest relative humidity is April (69%).
Average rainfall in September
Boston, MA
- Average rainfall in September: 1.26"
The wettest months (with the highest rainfall) are March, April and December (2.91").
The driest month (with the least rainfall) is September (1.26").
Average rainfall days in September
Boston, MA
- Average rainfall days in September: 10 days
The month with the highest number of rainy days is May (15.3 days).
The month with the least rainy days is January (7.9 days).
Average snowfall in September
Boston, MA
- Average snowfall in September: 0"
The month with the highest snowfall is February (4.72").
The months with the least snowfall are June, July, August and September (0").
Average snowfall days in September
Boston, MA
- Average snowfall days in September: 0 days
The months with the highest number of snowfall days are January and February (7.6 days).
The months with the least snowfall days are June, July, August and September (0 days).
Average sea temperature in September
Boston, MA
- Average sea temperature in September: 64.8°F
The best month for swimming (with the highest average sea temperature) is August (67.9°F).
The coldest month (with the lowest average sea temperature) is February (38.1°F).
Average daylight in September /
Average sunshine in September
Boston, MA
- Average daylight in September: 12h and 30min
The month with the longest days is June (Average daylight: 15h and 12min).
The month with the shortest days is December (Average daylight: 9h and 6min).
- Average sunshine in September: 8h and 24min
The month with the most sunshine is August (Average sunshine: 10h and 30min).
The month with the least sunshine is February (Average sunshine: 4h and 36min).
Average sunshine days in September
Boston, MA
- Average sunshine days in September: 17.7 days
The month with the most sunshine days is September (17.7 days).
The month with the least sunshine days is April (13 days).
Average UV index in September
Boston, MA
- Average UV index in September: 4
The months with the highest UV index are June, July and August (UV index 6).
The months with the lowest UV index are January, February, March, November and December (UV index 2).
Average cloud cover in September
Boston, MA
- Average cloud cover in September: 37
The month with the most cloud cover is March (Cloud cover 51).
The month with the least cloud cover is August (Cloud cover 32).
Average visibility in September
Boston, MA
- Average visibility in September: 6mi
The months with the highest visibility are January, February, March, April, May, June, July, August, September, October, November and December (6mi).
The months with the lowest visibility are January, February, March, April, May, June, July, August, September, October, November and December (6mi).
