September weather forecastSomerville, MA
September
Weather in September
September in Somerville Massachusetts sees the dawn of the fall season, with a noticeable drop in the highest temperature to 72.9°F (22.7°C) and the beginning of autumn colors. The winds start to pick up in frequency in comparison to the calm summer months. Evenings become cooler as the city prepares to welcome the fall season. The level of rainfall decreases to its lowest for the year, paving the way for a drier month. Sunshine hours witness a gradual decline, indicating the arrival of shorter days.Temperature
September's arrival signals a moderate reduction in the average high-temperature, easing from a warm 80.4°F (26.9°C) in August to an agreeable 72.9°F (22.7°C). An average temperature of 56.8°F (13.8°C) marks the nights in September.Humidity
The average relative humidity in September is 75%.Rainfall
The month with the least rainfall is September, when the rain falls for 2.9 days and typically collects 0.12" (3mm) of precipitation.Snowfall
June through October are months without snowfall in Somerville.Daylight
In Somerville, 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 7:18 pm. On the last day of the month, sunrise is at 6:41 am and sunset at 6:27 pm EDT.
Sunshine
In Somerville, the average sunshine in September is 8.5h.UV index
In Somerville, the average daily maximum UV index in September is 4. A UV Index of 3 to 5 symbolizes a moderate threat to health from unprotected exposure to Sun's UV rays for ordinary individuals.Note: An average UV index of 4 in September transforms into this advice:
Act with care - Obligation to protect against skin and eye damage is highlighted. The mid-day Sun emits the most powerful UV radiation, so seek shade and minimize exposure. A hat with a broad brim is indispensable, filtering out up to half of UV rays.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in September
Somerville, MA
- Average high temperature in September: 72.9°F
The warmest month (with the highest average high temperature) is July (81.9°F).
The month with the lowest average high temperature is January (33.8°F).
- Average low temperature in September: 56.8°F
The month with the highest average low temperature is July (64.8°F).
The coldest month (with the lowest average low temperature) is January (22.5°F).
Average pressure in September
Somerville, 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
Somerville, MA
- Average wind speed in September: 6.6mph
The windiest month (with the highest average wind speed) is January (9.6mph).
The calmest month (with the lowest average wind speed) is August (6mph).
Average humidity in September
Somerville, MA
- Average humidity in September: 75%
The month with the highest relative humidity is February (78%).
The month with the lowest relative humidity is April (69%).
Average rainfall in September
Somerville, MA
- Average rainfall in September: 0.12"
The wettest month (with the highest rainfall) is November (0.55").
The driest month (with the least rainfall) is September (0.12").
Average rainfall days in September
Somerville, MA
- Average rainfall days in September: 2.9 days
The month with the highest number of rainy days is April (5.9 days).
The months with the least rainy days are January and September (2.9 days).
Average snowfall in September
Somerville, MA
- Average snowfall in September: 0"
The month with the highest snowfall is December (0.71").
The months with the least snowfall are June, July, August, September and October (0").
Average snowfall days in September
Somerville, MA
- Average snowfall days in September: 0 days
The month with the highest number of snowfall days is January (3.4 days).
The months with the least snowfall days are June, July, August and September (0 days).
Average daylight in September /
Average sunshine in September
Somerville, 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 30min
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
Somerville, MA
- Average sunshine days in September: 24.8 days
The month with the most sunshine days is December (25.5 days).
The month with the least sunshine days is July (22.8 days).
Average UV index in September
Somerville, 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
Somerville, MA
- Average cloud cover in September: 37
The month with the most cloud cover is March (Cloud cover 50).
The month with the least cloud cover is August (Cloud cover 32).
Average visibility in September
Somerville, 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).
