Contents
- Weather in September
- Frequently asked questions
- Average temperature in September
- Average pressure in September
- Average wind speed in September
- Average humidity in September
- Average rainfall in September
- Average rainfall days in September
- Average snowfall in September
- Average snowfall days in September
- Average daylight in September
- Average sunshine in September
- Average sunshine days in September
- Average UV index in September
- Average cloud cover in September
- Average visibility in September
Weather in September
Temperature
September brings a decrease in the average high-temperature, shifting from a moderately hot 75.2°F (24°C) in August to a refreshing 65.7°F (18.7°C). With the onset of night in September, Garrison reveals a significant decrease in temperature, averaging at a cold 41.2°F (5.1°C).Humidity
In Garrison, the average relative humidity in September is 55%.Rainfall
In Garrison, in September, it is raining for 7.5 days, with typically 0.87" (22mm) of accumulated precipitation. Throughout the year, there are 122.8 rainfall days, and 17.13" (435mm) of precipitation is accumulated.Snowfall
Months with snowfall in Garrison are January through June, September through December. September is the first month it typically snows. Throughout September, in the average 1.3 snowfall days, it receives 2.24" (57mm) of snow. Throughout the year, there are 125.4 snowfall days, and 77.91" (1979mm) of snow is accumulated.Daylight
The average length of the day in September is 12h and 32min.On the first day of September, sunrise is at 6:52 am and sunset at 8:09 pm. On the last day of the month, sunrise is at 7:29 am and sunset at 7:12 pm MDT.
Sunshine
In September, the average sunshine is 9.6h.UV index
In Garrison, the average daily maximum UV index in September is 3. A UV Index estimate of 3 to 5 represents a moderate health risk from unprotected exposure to Sun's UV rays for ordinary individuals.Note: In September, the maximum UV index of 3 translates into these guidelines:
Be vigilant - Preventing sunburn is recommended. Midday is the peak time for the Sun's radiation; stay in the shade and protect yourself. For a sun-safe wardrobe, go for clothes that are tightly woven and generously sized. Keep in mind! Snow's reflective quality can nearly double the intensity of the Sun's UV radiation.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
What is the average September temperature in Garrison?
What is the average humidity in September?
How many days does it rain in September?
When does it start snowing?
What is the average length of the day in September in Garrison?
When is the sunrise / sunset in September?
How long on average sun shines in September?
What is the UV index reading in September?
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).
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).
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).
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%).
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").
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).
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").
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).
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).
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).
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).
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).
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).
Garrison, Montana, USA
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