September weather forecast
Cambridge, MA

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The John Weeks Memorial Footbridge in Cambridge, Massachusetts, over the Charles River calm waters, and a distant view of the Havard University student residence unit
The John Weeks Memorial Footbridge in Cambridge, Massachusetts, over the Charles River calm waters, and a distant view of the Havard University student residence unit

Weather in September

September stands as a transition month in Cambridge, Massachusetts, marking the shift from summer to autumn. The weather becomes cooler, and the deciduous trees begin showing hints of fall colors. Locals enjoy outdoor activities as the weather remains warm but not excessively hot. Temperatures display signs of falling towards year's end, wavering from 56.7°F (13.7°C) to 72.9°F (22.7°C). The city sees less rainfall, making it an ideal time to explore Cambridge's historical and architectural gems.

Temperature

In Cambridge, the beginning of September is marked by a marginally lowered average high-temperature, shifting from August's moderately hot 80.4°F (26.9°C) to a pleasant 72.9°F (22.7°C). In Cambridge, September's nights observe an average temperature dip to a mild 56.7°F (13.7°C).

Humidity

In September, the average relative humidity is 75%.

Rainfall

September is the month with the least rainfall. Rain falls for 6.4 days and accumulates 0.2" (5mm) of precipitation.

Snowfall

In Cambridge, snow does not fall in June through October.

Daylight

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

The average sunshine in September is 8.5h.

UV index

In September, the average daily maximum UV index is 4. A UV Index of 3 to 5 symbolizes a moderate threat to health from exposure to the Sun's UV radiation for ordinary individuals.
Note: In September, the maximum UV index of 4 suggests these recommendations:
Safety measures are advised. Light-skinned individuals may experience burns in under half an hour. The Sun's most intense and consequently most harmful UV radiation during midday hours should be decreased by minimizing exposure and seeking shade. Employ a hat with a wide brim for robust protection, cutting UV exposure by half.
Updated: Aug 31, 2024
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate

Frequently asked questions

What are September temperatures?

In Cambridge, in September, the average high-temperature is 72.9°F (22.7°C), and the average low-temperature is 56.7°F (13.7°C). In July, the average heat index (a.k.a. 'felt air temperature', 'feels like'), which factors the actual air temperature with the relative humidity, is calculated to be 86°F (30°C).

What is the average humidity in September?

In September, the average relative humidity is 75%.

What is the driest month?

The month with the least rainfall is September, when the rain falls for 6.4 days and typically collects 0.2" (5mm) of precipitation.

How many days does it rain in September?

In Cambridge, in September, it is raining for 6.4 days, with typically 0.2" (5mm) of accumulated precipitation.

When it does not snow?

In Cambridge, snow does not fall in June through October.

How many hours of daylight does Cambridge have in September?

In Cambridge, the average day length in September is 12h and 28min.

When is the sunrise / sunset in September?

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.

How long on average sun shines in September?

The average sunshine duration in September is 8.5h.

How high is the UV index in September?

The average daily maximum UV index in September is 4. A UV Index reading of 3 to 5 represents a medium health risk from exposure to the Sun's UV radiation.
Average humidity
Average rainfall days
Average snowfall
Average snowfall days
Average daylight
Average sunshine
Average sunshine days
Average UV index
Average cloud cover
Average visibility

Average temperature in September
Cambridge, MA

Average temperature in September - Cambridge, 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: 56.7°F

The month with the highest average low temperature is July (64.6°F).
The coldest month (with the lowest average low temperature) is January (22.5°F).

Average pressure in September
Cambridge, MA

Average pressure in September - Cambridge, 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
Cambridge, MA

Average wind speed in September - Cambridge, MA
  • Average wind speed in September: 6.6mph

The windiest month (with the highest average wind speed) is January (9.5mph).
The calmest month (with the lowest average wind speed) is August (6mph).

Average humidity in September
Cambridge, MA

Average humidity in September - Cambridge, MA
  • Average humidity in September: 75%

The months with the highest relative humidity are January and February (77%).
The month with the lowest relative humidity is April (69%).

Average rainfall in September
Cambridge, MA

Average rainfall in September - Cambridge, MA
  • Average rainfall in September: 0.2"

The wettest month (with the highest rainfall) is November (0.63").
The driest month (with the least rainfall) is September (0.2").

Average rainfall days in September
Cambridge, MA

Average rainfall days in September - Cambridge, MA
  • Average rainfall days in September: 6.4 days

The month with the highest number of rainy days is July (9.6 days).
The month with the least rainy days is January (4.3 days).

Average snowfall in September
Cambridge, MA

Average snowfall in September - Cambridge, 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
Cambridge, MA

Average snowfall days in September - Cambridge, MA
  • Average snowfall days in September: 0 days

The month with the highest number of snowfall days is January (4.8 days).
The months with the least snowfall days are June, July, August, September and October (0 days).

Average daylight in September /
Average sunshine in September
Cambridge, MA

Average daylight in September / Average sunshine in September - Cambridge, MA
  • Average daylight in September: 12h and 3min

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 3min

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 42min).

Average sunshine days in September
Cambridge, MA

Average sunshine days in September - Cambridge, MA
  • Average sunshine days in September: 21.8 days

The month with the most sunshine days is January (23.5 days).
The month with the least sunshine days is June (17.4 days).

Average UV index in September
Cambridge, MA

Average UV index in September - Cambridge, 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
Cambridge, MA

Average cloud cover in September - Cambridge, MA
  • Average cloud cover in September: 36

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
Cambridge, MA

Average visibility in September - Cambridge, 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).

Cambridge, Massachusetts, USA

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