September weather forecast
Arlington, MA

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Weather in September

September in Arlington, Massachusetts signals the start of the fall season with a noticeable drop in temperatures from August. The cooling trend is carried from August, with September ushering in the richness of the autumn season. Highlighting September's weather transition, this month records the least amount of rainfall with just 1.3" (33mm). The arrival of October presents a continuation of diminishing temperatures. The spectacle of changing leaf colors throughout September provides a picturesque backdrop to the natural landscapes.

Temperature

September brings a slight decrease in the average high-temperature, shifting from a moderately hot 80.8°F (27.1°C) in August to an agreeable 73°F (22.8°C). During September, the nighttime temperature averages to a moderate 56.5°F (13.6°C).

Humidity

In September, the average relative humidity is 75%.

Rainfall

September is the month with the least rainfall. Rain falls for 10.7 days and accumulates 1.3" (33mm) of precipitation.

Snowfall

In Arlington, Massachusetts, snow does not fall in June through September.

Daylight

The average length of the day in September in Arlington is 12h and 29min.
On the first day of the month, sunrise is at 6:10 am and sunset at 7:18 pm. On the last day of September, in Arlington, sunrise is at 6:41 am and sunset at 6:27 pm EDT.

Sunshine

In September, the average sunshine in Arlington is 8.5h.

UV index

The average daily maximum UV index in September in Arlington is 4. A UV Index reading of 3 to 5 represents a moderate health risk from unprotected exposure to Sun's UV rays for the average person.
Note: The maximum daily UV index of 4 in September converts into the following recommendations:
Stay alert. Light-skinned people could suffer burns in less than 30 minutes. Around midday, solar radiation is most harmful; hence, exposure should be limited. A wide-brimmed hat provides unparalleled sun protection for sensitive areas like the eyes, ears, and neck.
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Frequently asked questions

What is the usual temperature for Arlington in September?

The high-temperature, in September, in Arlington, is 73°F (22.8°C), while the low-temperature averages to 56.5°F (13.6°C). The average heat index (a.k.a. 'feels like', 'real feel'), which calculates the temperature value influenced by the moisture in the air, in August is appraised at 84.2°F (29°C).

What is the average humidity in September in Arlington?

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

What is the driest month in Arlington?

September is the month with the least rainfall. Rain falls for 10.7 days and accumulates 1.3" (33mm) of precipitation.

How many days does it rain in September in Arlington?

In Arlington, Massachusetts, in September, during 10.7 rainfall days, 1.3" (33mm) of precipitation is typically accumulated.

When it does not snow in Arlington?

In Arlington, Massachusetts, snow does not fall in June through September.

Does it snow in Arlington in September?

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

What is the average length of the day in September in Arlington?

In September, the average day length in Arlington, Massachusetts, is 12h and 29min.

What time are sunrise and sunset in September in Arlington?

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 in Arlington?

In Arlington, Massachusetts, the average sunshine duration in September is 8.5h.

How high is the UV index in September in Arlington?

The average daily maximum UV index in September in Arlington, Massachusetts, is 4. A UV Index value of 3 to 5 symbolizes a medium hazard to health from exposure to Sun's UV rays.
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
Arlington, MA

Average temperature in September - Arlington, MA
  • Average high temperature in September: 73°F

The warmest month (with the highest average high temperature) is July (82°F).
The month with the lowest average high temperature is January (33.4°F).

  • Average low temperature in September: 56.5°F

The month with the highest average low temperature is July (64.4°F).
The coldest month (with the lowest average low temperature) is January (21.7°F).

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Average pressure in September
Arlington, MA

Average pressure in September - Arlington, MA
  • Average pressure in September: 30.05"Hg

The month with the highest atmospheric pressure is November (30.07"Hg).
The month with the lowest atmospheric pressure is June (29.92"Hg).

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Average wind speed in September
Arlington, MA

Average wind speed in September - Arlington, MA
  • Average wind speed in September: 6.5mph

The windiest month (with the highest average wind speed) is January (9.4mph).
The calmest month (with the lowest average wind speed) is August (5.9mph).

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Average humidity in September
Arlington, MA

Average humidity in September - Arlington, 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 (70%).

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Average rainfall in September
Arlington, MA

Average rainfall in September - Arlington, MA
  • Average rainfall in September: 1.3"

The wettest month (with the highest rainfall) is December (2.95").
The driest month (with the least rainfall) is September (1.3").

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Average rainfall days in September
Arlington, MA

Average rainfall days in September - Arlington, MA
  • Average rainfall days in September: 10.7 days

The months with the highest number of rainy days are May and July (15.3 days).
The month with the least rainy days is January (7.8 days).

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Average snowfall in September
Arlington, MA

Average snowfall in September - Arlington, 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
Arlington, MA

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

The month with the highest number of snowfall days is January (7.7 days).
The months with the least snowfall days are June, July, August and September (0 days).

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

Average daylight in September / Average sunshine in September - Arlington, 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).

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Average sunshine days in September
Arlington, MA

Average sunshine days in September - Arlington, MA
  • Average sunshine days in September: 17.4 days

The month with the most sunshine days is November (17.6 days).
The month with the least sunshine days is April (13.3 days).

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Average UV index in September
Arlington, MA

Average UV index in September - Arlington, 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
Arlington, MA

Average cloud cover in September - Arlington, 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).

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Average visibility in September
Arlington, MA

Average visibility in September - Arlington, MA
  • Average visibility in September: 6mi

The months with the highest visibility are January, March, April, May, June, July, August, September, October, November and December (6mi).
The month with the lowest visibility is February (5mi).

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Arlington, Massachusetts, USA

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