September weather forecast
Acton, MT

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Weather in September

The first month of the autumn, September, is still a pleasant month in Acton, Montana, with an average temperature varying between 73.2°F (22.9°C) and 52.5°F (11.4°C).

Temperature

As September arrives, Acton's weather displays a decrease in high-temperatures, transitioning from August's moderately hot 83.5°F (28.6°C) to an agreeable 73.2°F (22.9°C). In Acton, an average nighttime temperature of 52.5°F (11.4°C) is expected during September.

Humidity

In September, the average relative humidity in Acton is 44%.

Rainfall

In September, in Acton, Montana, the rain falls for 6.8 days. Throughout September, 0.67" (17mm) of precipitation is accumulated. In Acton, during the entire year, the rain falls for 120.5 days and collects up to 13.54" (344mm) of precipitation.

Snowfall

January through May, September through December are months with snowfall in Acton, Montana. September is the first month it typically snows in Acton. Throughout September, in the average 0.2 snowfall days, it receives 0.12" (3mm) of snow. In Acton, during the entire year, snow falls for 68.6 days and aggregates up to 32.56" (827mm) of snow.

Daylight

In September, the average length of the day is 12h and 31min.
On the first day of September in Acton, sunrise is at 6:36 am and sunset at 7:52 pm. On the last day of the month, sunrise is at 7:12 am and sunset at 6:56 pm MDT.

Sunshine

In September, the average sunshine in Acton is 10.3h.

UV index

The average daily maximum UV index in September is 4. A UV Index value of 3 to 5 symbolizes a moderate health risk from unprotected exposure to Sun's UV rays for the ordinary person.
Note: A typical high UV index of 4 in September suggests the following recommendations:
Take necessary precautions - Defending against sun damage is advocated. When the Sun's UV radiation is most intense during midday, it's best to find shade and limit exposure. Experience reduced UV exposure by about half when donning a wide-brim hat. Be aware! The reflective nature of snow can magnify the Sun's UV radiation almost twofold.
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Frequently asked questions

What are the temperatures in Acton in September?

An average high-temperature, in September, in Acton, is 73.2°F (22.9°C) and the average low-temperature is 52.5°F (11.4°C). In August, the average heat index (a.k.a. 'real feel', 'feels like'), which calculates the temperature value influenced by the moisture in the air, is appraised at 82.4°F (28°C).

What is the average humidity in September in Acton?

In September, the average relative humidity in Acton, Montana, is 44%.

How many days does it rain in September in Acton?

In Acton, Montana, in September, during 6.8 rainfall days, 0.67" (17mm) of precipitation is typically accumulated.

When does it start to snow in Acton?

September is the first month it typically snows in Acton, Montana. Throughout September, in the average 0.2 snowfall days, it receives 0.12" (3mm) of snow.

How many hours of daylight does Acton have in September?

In Acton, Montana, the average day length in September is 12h and 31min.

When is the sunrise / sunset in September in Acton?

In September, on the first day of the month, sunrise is at 6:36 am and sunset at 7:52 pm. On the last day of the month, in Acton, sunrise is at 7:12 am and sunset at 6:56 pm MDT.

How many hours of sunshine does Acton have in September?

In September, the average sunshine duration in Acton is 10.3h.

What is the UV index reading in September in Acton?

In September, the average daily maximum UV index is 4. A UV Index estimate of 3 to 5 represents a medium hazard to health from unprotected exposure to UV radiation.
Average humidity
Average rainfall days
Average snowfall days
Average daylight
Average sunshine
Average sunshine days
Average UV index
Average cloud cover
Average visibility

Average temperature in September
Acton, MT

Average temperature in September - Acton, MT
  • Average high temperature in September: 73.2°F

The warmest month (with the highest average high temperature) is July (85.5°F).
The month with the lowest average high temperature is December (31.1°F).

  • Average low temperature in September: 52.5°F

The months with the highest average low temperature are July and August (60.6°F).
The coldest month (with the lowest average low temperature) is February (18.3°F).

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Average pressure in September
Acton, MT

Average pressure in September - Acton, MT
  • Average pressure in September: 29.95"Hg

The month with the highest atmospheric pressure is January (30.14"Hg).
The month with the lowest atmospheric pressure is June (29.86"Hg).

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Average wind speed in September
Acton, MT

Average wind speed in September - Acton, MT
  • Average wind speed in September: 8.1mph

The windiest month (with the highest average wind speed) is January (9.9mph).
The calmest month (with the lowest average wind speed) is July (7.1mph).

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Average humidity in September
Acton, MT

Average humidity in September - Acton, MT
  • Average humidity in September: 44%

The month with the highest relative humidity is January (76%).
The month with the lowest relative humidity is August (40%).

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Average rainfall in September
Acton, MT

Average rainfall in September - Acton, MT
  • Average rainfall in September: 0.67"

The wettest month (with the highest rainfall) is May (2.24").
The driest month (with the least rainfall) is July (0.43").

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Average rainfall days in September
Acton, MT

Average rainfall days in September - Acton, MT
  • Average rainfall days in September: 6.8 days

The month with the highest number of rainy days is May (17.8 days).
The month with the least rainy days is January (5.6 days).

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Average snowfall in September
Acton, MT

Average snowfall in September - Acton, MT
  • Average snowfall in September: 0.12"

The month with the highest snowfall is February (6.61").
The months with the least snowfall are June, July and August (0").

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Average snowfall days in September
Acton, MT

Average snowfall days in September - Acton, MT
  • Average snowfall days in September: 0.2 days

The month with the highest number of snowfall days is February (14.3 days).
The months with the least snowfall days are June, July and August (0 days).

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Average daylight in September /
Average sunshine in September
Acton, MT

Average daylight in September / Average sunshine in September - Acton, MT
  • Average daylight in September: 12h and 3min

The month with the longest days is June (Average daylight: 15h and 42min).
The month with the shortest days is December (Average daylight: 8h and 42min).

  • Average sunshine in September: 10h and 2min

The month with the most sunshine is July (Average sunshine: 11h and 54min).
The month with the least sunshine is February (Average sunshine: 5h and 18min).

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Average sunshine days in September
Acton, MT

Average sunshine days in September - Acton, MT
  • Average sunshine days in September: 21.1 days

The month with the most sunshine days is September (21.1 days).
The month with the least sunshine days is April (9.8 days).

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Average UV index in September
Acton, MT

Average UV index in September - Acton, MT
  • Average UV index in September: 4

The month with the highest UV index is July (UV index 7).
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
Acton, MT

Average cloud cover in September - Acton, MT
  • Average cloud cover in September: 20

The month with the most cloud cover is February (Cloud cover 46).
The month with the least cloud cover is July (Cloud cover 14).

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Average visibility in September
Acton, MT

Average visibility in September - Acton, MT
  • 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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Acton, Montana, USA

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