September weather forecast and climate
Garrison, MT

Weather in September

The first month of the autumn, September, is also an enjoyable month in Garrison, Montana, with temperature in the range of an average low of 41.2°F (5.1°C) and an average high of 65.7°F (18.7°C).

Temperature

In September, the average high-temperature decreases, from a warm 75.2°F (24°C) in August, to an enjoyable 65.7°F (18.7°C). In Garrison, the average low-temperature is 41.2°F (5.1°C).

Humidity

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

Rainfall

In Garrison, during September, the rain falls for 7.5 days and regularly aggregates up to 0.87" (22mm) of precipitation. In Garrison, during the entire year, the rain falls for 122.8 days and collects up to 17.13" (435mm) of precipitation.

Snowfall

January through June, September through December are months with snowfall. September is the first month it typically snows. Throughout September, in the average 1.3 snowfall days, it receives 2.24" (57mm) of snow. In Garrison, during the entire year, snow falls for 125.4 days, and aggregates up to 77.91" (1979mm) of snow.

Daylight

The average length of the day in Garrison is 12.5h.

Sunshine

The average sunshine in Garrison is 9.6h.

UV index

In September, the average daily maximum UV index in Garrison is 3. A UV Index of 3 to 5 symbolizes a moderate threat to health from unsafe exposure to the UV radiation for average individuals.
Note: The average daily UV index of 3 in September transform into the following instructions:
Take precautions - Protection against the skin and eye damage is obliged. The Sun's most intense and consequently most harmful UV radiation during midday hours should be decreased by minimizing exposure and seeking shade. Sun-protective clothing, a long-sleeved shirt and pants, a wide-brimmed hat, and UVA and UVB-blocking sunglasses are particularly helpful in blocking UV radiation's harmful effects. Beware! The strength of the UV rays is increased nearly double-fold by the reflection of the snow.
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FAQ

What is the temperature in September in Garrison?

In Garrison, Montana, in September, the average high-temperature is 65.7°F (18.7°C), and the average low-temperature is 41.2°F (5.1°C).

What is the average humidity in September in Garrison?

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

How much does it rain in Garrison in September?

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

When does it start to snow in Garrison?

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

How many hours of daylight does Garrison have in September?

In September, the average length of the day is 12.5h.

How many hours of sunshine does Garrison have in September?

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

What is the UV index reading in September in Garrison?

In September, the average daily maximum UV index in Garrison is 3. A UV Index of 3 to 5 symbolizes a medium hazard to health from unsafe exposure to the Sun's UV rays.

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"

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

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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%

Months with the highest relative humidity are January and February (88%).
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").
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).
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: 12.5h

The month with the longest days is June (Average daylight: 15.8h).
The month with the shortest days is December (Average daylight: 8.6h).

  • Average sunshine in September: 9.6h

The month with the most sunshine is July (Average sunshine: 11.7h).
The month with the least sunshine is January (Average sunshine: 5.6h).

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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).
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).
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

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

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