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
With September's onset, the average high-temperature recedes from August's moderately hot 81.9°F (27.7°C) to a pleasant 71.2°F (21.8°C). September witnesses an average nighttime temperature of 50.5°F (10.3°C).Humidity
In Great Falls, the average relative humidity in September is 46%.Rainfall
In September, the rain falls for 5.3 days. Throughout September, 0.31" (8mm) of precipitation is accumulated. In Great Falls, during the entire year, the rain falls for 68.2 days and collects up to 4.49" (114mm) of precipitation.Snowfall
Months with snowfall are January through May, September through December. September is the first month it typically snows. Throughout September, in the average 0.5 snowfall days, it receives 0.79" (20mm) of snow. In Great Falls, during the entire year, snow falls for 45.4 days and aggregates up to 11.61" (295mm) of snow.Daylight
In Great Falls, the average length of the day in September is 12h and 33min.On the first day of September, sunrise is at 6:45 am and sunset at 8:04 pm. On the last day of the month, sunrise is at 7:23 am and sunset at 7:05 pm MDT.
Sunshine
The average sunshine in September is 9.7h.UV index
In September, the average daily maximum UV index is 4. A UV Index estimate of 3 to 5 represents a moderate health risk from unsafe exposure to UV radiation for average individuals.Note: An average UV index of 4 in September transforms into this advice:
Undertake protective steps - Recommendations to avoid sunburn are issued. The solar radiation around mid-day is intense; avoid the Sun and stay safe. Sunglasses that guard against UVA and UVB rays are pivotal in minimizing sun-induced ocular damage. Alert! The snow's reflection can amplify the UV radiation of the Sun nearly twice.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
What are September temperatures?
What is the average humidity in September?
How much does it rain in September?
When does it start snowing?
What is the average length of the day in September?
When is the sunrise / sunset in September?
How long on average sun shines in September?
What is the UV index intensity in September?
Average temperature in September
Great Falls, MT
- Average high temperature in September: 71.2°F
The warmest month (with the highest average high temperature) is July (83.1°F).
The month with the lowest average high temperature is December (30°F).
- Average low temperature in September: 50.5°F
The month with the highest average low temperature is August (57.7°F).
The coldest months (with the lowest average low temperature) are February and December (18.3°F).
Average pressure in September
Great Falls, 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 (29.87"Hg).
Average wind speed in September
Great Falls, MT
- Average wind speed in September: 8.6mph
The windiest month (with the highest average wind speed) is November (11.4mph).
The calmest month (with the lowest average wind speed) is August (7.7mph).
Average humidity in September
Great Falls, MT
- Average humidity in September: 46%
The month with the highest relative humidity is January (77%).
The month with the lowest relative humidity is August (40%).
Average rainfall in September
Great Falls, MT
- Average rainfall in September: 0.31"
The wettest month (with the highest rainfall) is June (0.87").
The driest month (with the least rainfall) is December (0.16").
Average rainfall days in September
Great Falls, MT
- Average rainfall days in September: 5.3 days
The month with the highest number of rainy days is April (9.9 days).
The month with the least rainy days is December (2.7 days).
Average snowfall in September
Great Falls, MT
- Average snowfall in September: 0.79"
The month with the highest snowfall is February (2.09").
The months with the least snowfall are June, July and August (0").
Average snowfall days in September
Great Falls, MT
- Average snowfall days in September: 0.5 days
The month with the highest number of snowfall days is February (10 days).
The months with the least snowfall days are June, July and August (0 days).
Average daylight in September /
Average sunshine in September
Great Falls, MT
- Average daylight in September: 12h and 3min
The month with the longest days is June (Average daylight: 15h and 54min).
The month with the shortest days is December (Average daylight: 8h and 30min).
- Average sunshine in September: 9h and 4min
The month with the most sunshine is July (Average sunshine: 12h and 6min).
The months with the least sunshine are January, February and December (Average sunshine: 5h and 30min).
Average sunshine days in September
Great Falls, MT
- Average sunshine days in September: 23.6 days
The month with the most sunshine days is July (26.1 days).
The months with the least sunshine days are February and April (16.2 days).
Average UV index in September
Great Falls, MT
- Average UV index in September: 4
The month with the highest UV index is July (UV index 6).
The months with the lowest UV index are January, February, March, October, November and December (UV index 2).
Average cloud cover in September
Great Falls, MT
- Average cloud cover in September: 23
The month with the most cloud cover is February (Cloud cover 46).
The month with the least cloud cover is July (Cloud cover 13).
Average visibility in September
Great Falls, 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).
Great Falls, Montana, USA
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