September weather forecast
Garrison, MT

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Weather in September

September, the first month of the autumn in Garrison, is also an enjoyable month, with an average temperature varying between 41.2°F (5.1°C) and 65.7°F (18.7°C).

Temperature

The onset of September comes with a shift in the average high-temperature, falling from a warm 75.2°F (24°C) in August to a refreshing 65.7°F (18.7°C). In Garrison, a significant divergence from daytime highs is recorded, with average lows of 41.2°F (5.1°C) during September nights.

Humidity

In September, the average relative humidity is 55%.

Rainfall

In Garrison, Montana, in September, during 7.5 rainfall days, 0.87" (22mm) of precipitation is typically accumulated. Throughout the year, in Garrison, there are 122.8 rainfall days, and 17.13" (435mm) of precipitation is accumulated.

Snowfall

Months with snowfall are January through June, September through December. September is the first month it typically snows in Garrison. Throughout September, in the average 1.3 snowfall days, it receives 2.24" (57mm) of snow. Throughout the year, in Garrison, there are 125.4 snowfall days, and 77.91" (1979mm) of snow is accumulated.

Daylight

In Garrison, Montana, the average length of the day in September is 12h and 32min.
On the first day of the month, sunrise is at 6:52 am and sunset at 8:09 pm. On the last day of September, sunrise is at 7:29 am and sunset at 7:12 pm MDT.

Sunshine

In Garrison, the average sunshine in September is 9.6h.

UV index

In Garrison, the average daily maximum UV index in September is 3. A UV Index value of 3 to 5 symbolizes a medium vulnerability from unprotected exposure to Sun's UV rays for the average person.
Note: The daily high UV index of 3 during September translates into the following recommendations:
Act with care - The need to guard against sun damage is communicated. Sun exposure should be minimized, especially during midday, to avoid harmful UV radiation. Consider a wide-brim hat essential for effective sun defense covering your face, neck, and eyes. Beware! Reflection from snow can magnify the Sun's UV radiation nearly twofold.
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Frequently asked questions

What is the temperature in September in Garrison?

The high-temperature, in September, in Garrison, records 65.7°F (18.7°C), while the low-temperature is 41.2°F (5.1°C).

What is the average humidity in September in Garrison?

In Garrison, the average relative humidity in September is 55%.

How much does it rain in Garrison in September?

In Garrison, Montana, during September, the rain falls for 7.5 days and regularly aggregates up to 0.87" (22mm) of precipitation.

When does it start snowing in Garrison?

September is the first month it typically snows in Garrison. Throughout September, in the average 1.3 snowfall days, it receives 2.24" (57mm) of snow.

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

The average day length in September is 12h and 32min.

When is the sunrise / sunset in September in Garrison?

In September, on the first day of the month, sunrise is at 6:52 am and sunset at 8:09 pm. On the last day of the month, in Garrison, sunrise is at 7:29 am and sunset at 7:12 pm MDT.

How long on average sun shines in September in Garrison?

The average sunshine duration in September is 9.6h.

What is the UV index reading in September in Garrison?

In September, the average daily maximum UV index is 3. A UV Index reading of 3 to 5 represents a moderate vulnerability from exposure to Sun's UV rays.
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
Garrison, MT

Average temperature in September - Garrison, MT
  • Average high temperature in September: 65.7°F

The warmest month (with the highest average high temperature) is July (76.8°F).
The month with the lowest average high temperature is December (25.7°F).

  • Average low temperature in September: 41.2°F

The month with the highest average low temperature is August (47.3°F).
The coldest month (with the lowest average low temperature) is December (12.6°F).

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Average pressure in September
Garrison, MT

Average pressure in September - Garrison, MT
  • Average pressure in September: 29.98"Hg

The months with the highest atmospheric pressure are January and December (30.19"Hg).
The month with the lowest atmospheric pressure is June (29.92"Hg).

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Average wind speed in September
Garrison, MT

Average wind speed in September - Garrison, MT
  • Average wind speed in September: 5.4mph

The windiest months (with the highest average wind speed) are January, April and November (6.3mph).
The calmest month (with the lowest average wind speed) is August (4.8mph).

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Average humidity in September
Garrison, MT

Average humidity in September - Garrison, MT
  • Average humidity in September: 55%

The months with the highest relative humidity are January and February (88%).
The months with the lowest relative humidity are July and August (49%).

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Average rainfall in September
Garrison, MT

Average rainfall in September - Garrison, MT
  • Average rainfall in September: 0.87"

The wettest month (with the highest rainfall) is June (2.52").
The driest month (with the least rainfall) is August (0.67").

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Average rainfall days in September
Garrison, MT

Average rainfall days in September - Garrison, MT
  • Average rainfall days in September: 7.5 days

The month with the highest number of rainy days is May (17 days).
The month with the least rainy days is August (7.3 days).

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Average snowfall in September
Garrison, MT

Average snowfall in September - Garrison, MT
  • Average snowfall in September: 2.24"

The month with the highest snowfall is February (12.76").
The months with the least snowfall are July and August (0").

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Average snowfall days in September
Garrison, MT

Average snowfall days in September - Garrison, MT
  • Average snowfall days in September: 1.3 days

The month with the highest number of snowfall days is February (20.3 days).
The months with the least snowfall days are July and August (0 days).

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

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

The month with the longest days is June (Average daylight: 15h and 48min).
The month with the shortest days is December (Average daylight: 8h and 36min).

  • Average sunshine in September: 9h and 4min

The month with the most sunshine is July (Average sunshine: 11h and 42min).
The month with the least sunshine is January (Average sunshine: 5h and 36min).

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Average sunshine days in September
Garrison, MT

Average sunshine days in September - Garrison, MT
  • Average sunshine days in September: 19.9 days

The month with the most sunshine days is July (21.5 days).
The month with the least sunshine days is April (6.3 days).

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Average UV index in September
Garrison, MT

Average UV index in September - Garrison, MT
  • Average UV index in September: 3

The month with the highest UV index is July (UV index 5).
The months with the lowest UV index are January, February, March, April, October, November and December (UV index 2).

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Average cloud cover in September
Garrison, MT

Average cloud cover in September - Garrison, MT
  • Average cloud cover in September: 22

The month with the most cloud cover is February (Cloud cover 50).
The months with the least cloud cover are July and August (Cloud cover 15).

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Average visibility in September
Garrison, MT

Average visibility in September - Garrison, MT
  • Average visibility in September: 6mi

The months with the highest visibility are May, June, July, August, September and October (6mi).
The months with the lowest visibility are January, February, March and December (4mi).

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Garrison, Montana, USA

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