September weather forecast
Boston, MA

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A beautiful natural park with the George Washington Monument in Boston, Massachusetts
A beautiful natural park with the George Washington Monument in Boston, Massachusetts

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 and 57.4°F 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

The onset of September results in a small decrease in the average high-temperature, moderately receding from a moderately hot 80.4°F in August to a pleasant 72.7°F. Throughout the month of September, Boston reports a steady low-temperature average of 57.4°F.

Humidity

In Boston, the average relative humidity in September is 75%.

Rainfall

The month with the least rainfall in Boston, Massachusetts, is September, when the rain falls for 10 days and typically collects 1.26" 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.
Note: Swimming in water with a temperature of 64.8°F is not a pleasurable experience for the majority. As the temperature falls below 69.8°F, it becomes increasingly hard to control one's breathing.

Daylight

The average length of the day in September is 12h and 28min.
On the first day of the month, sunrise is at 6:09 am and sunset at 7:19 pm. On the last day of September, in Boston, sunrise is at 6:40 am and sunset at 6:28 pm EDT.

Sunshine

In Boston, Massachusetts, 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 moderate threat to health from unsafe exposure to UV radiation for the ordinary person.
Note: The maximum daily UV index of 4 during September translates into the following directions:
Heed the precautions - Protecting the skin and eyes from damage is compulsory. Midday is the peak time for the Sun's radiation; stay in the shade and protect yourself. A wide-brimmed hat is a shield, deflecting up to 50% of harmful UV radiation from eyes.
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FAQ

What is the temperature in September in Boston?

In September, in Boston, the average high-temperature is 72.7°F, and the average low-temperature is 57.4°F. The average heat index (a.k.a. 'felt air temperature', 'real feel'), which calculates the temperature value influenced by the moisture in the air, in July is evaluated at 86°F.

What is the average humidity in September in Boston?

In September, the average relative humidity is 75%.

What is the driest month in Boston?

September is the month with the least rainfall. Rain falls for 10 days and accumulates 1.26" of precipitation.

How many days does it rain in September in Boston?

In September, in Boston, Massachusetts, the rain falls for 10 days. Throughout September, 1.26" of precipitation is accumulated.

When it does not snow in Boston?

June through September are months without snowfall in Boston.

Does it snow in Boston in September?

In Boston, Massachusetts, in September, it doesn't snow. In October, it regularly snows.

What is the ocean temperature in September in Boston?

In September, the average ocean temperature in Boston is 64.8°F. Swimming in 64.8°F is not enjoyable for the majority. Controlling breathing becomes progressively more difficult as surface water temperature decreases below 69.8°F.

How many hours of daylight does Boston have in September?

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

When is the sunrise / sunset in September in Boston?

On the first day of September in Boston, sunrise is at 6:09 am and sunset at 7:19 pm. On the last day of the month, sunrise is at 6:40 am and sunset at 6:28 pm EDT.

How many hours of sunshine does Boston have in September?

In September, the average sunshine duration in Boston, Massachusetts, is 8.4h.

How high is the UV index in September in Boston?

In September, the average daily maximum UV index in Boston is 4. A UV Index value of 3 to 5 symbolizes a moderate vulnerability from unprotected exposure to UV radiation.
Average high temperature
Average low temperature
Average pressure
Average wind speed
Average max. wind speed
Average wind speed gusts
Average humidity
Average rainfall
Average rainfall days
Average snowfall
Average snowfall days
Average sea temperature
Average daylight
Average sunshine
Average sunshine days
Average UV index
Average cloud cover
Average visibility

Average temperature in September
Boston, MA

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).

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Average pressure in September
Boston, MA

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).

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Average wind speed in September
Boston, MA

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).

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Average humidity in September
Boston, MA

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%).

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Average rainfall in September
Boston, MA

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").

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Average rainfall days in September
Boston, MA

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).

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Average snowfall in September
Boston, MA

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").

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Average snowfall days in September
Boston, MA

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).

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Average sea temperature in September
Boston, MA

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).

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

Average daylight in September / Average sunshine in September - Boston, 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 2min

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).

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Average sunshine days in September
Boston, MA

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).

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Average UV index in September
Boston, MA

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).

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Average cloud cover in September
Boston, MA

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).

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Average visibility in September
Boston, MA

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).

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Boston, Massachusetts, USA

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