Great Falls (MT)
September
Weather in Great Falls, Montana for September 2026
Your guide to Great Falls weather in September - trends and predictions
In general, the average temperature in Great Falls at the beginning of September is 26.9 °F. As the month progressed, temperatures tended to remain steady, reaching an average of 26.9 °F by the end of September.
With an average of 5 rainy days, Great Falls experiences minimal rainfall in September.
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Temperatures
Rain 🌧️
More
25
Dry days
5
Rainy days
0
Snow days
26°/9°
Temperatures
22 km/h
Avg max wind
50 %
Avg humidity
Great Falls Weather September
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Temperatures trend during September in Great Falls
See the weather trend as well as the moving average line
September weather in Great Falls day by day
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| Date | Weather | Temperatures | Rain | UV | More |
|---|---|---|---|---|---|
| Sept. 1 |  Sunny | 32° /12° | 0 mm | 7 | |
| Sept. 2 |  Overcast | 33° /13° | 0 mm | 7 | |
| Sept. 3 | Sunny | 28° /13° | 0 mm | 7 | |
| Sept. 4 | Overcast | 19° /12° | 0 mm | 6 | |
| Sept. 5 | Sunny | 21° /4° | 0 mm | 6 | |
| Sept. 6 | Sunny | 26° /4° | 0 mm | 6 | |
| Sept. 7 |  Thundery outbreaks possible | 29° /9° | 0 mm | 6 | |
| Sept. 8 | Thundery outbreaks possible | 29° /14° | 0 mm | 6 | |
| Sept. 9 | Overcast | 27° /10° | 3.8 mm | 6 | |
| Sept. 10 | Thundery outbreaks possible | 28° /11° | 0 mm | 6 | |
| Sept. 11 |  Fog | 27° /11° | 0 mm | 5 | |
| Sept. 12 |  Light rain shower | 23° /12° | 6 mm | 4 | |
| Sept. 13 | Mist | 24° /10° | 0 mm | 5 | |
| Sept. 14 | Mist | 27° /8° | 0 mm | 5 | |
| Sept. 15 | Overcast | 17° /14° | 4.4 mm | 2 | |
| Sept. 16 |  Cloudy | 23° /12° | 0 mm | 5 | |
| Sept. 17 | Sunny | 26° /9° | 0 mm | 5 | |
| Sept. 18 | Sunny | 26° /7° | 0 mm | 5 | |
| Sept. 19 | Overcast | 25° /9° | 0 mm | 5 | |
| Sept. 20 | Sunny | 30° /8° | 0 mm | 4 | |
| Sept. 21 | Cloudy | 27° /9° | 2.4 mm | 5 | |
| Sept. 22 | Patchy rain possible | 18° /10° | 21.8 mm | 2 | |
| Sept. 23 | Sunny | 26° /3° | 0 mm | 4 | |
| Sept. 24 | Sunny | 29° /6° | 0 mm | 4 | |
| Sept. 25 | Sunny | 29° /8° | 0 mm | 4 | |
| Sept. 26 | Sunny | 23° /8° | 0 mm | 4 | |
| Sept. 27 | Sunny | 27° /5° | 0 mm | 4 | |
| Sept. 28 | Sunny | 27° /5° | 0 mm | 4 | |
| Sept. 29 | Sunny | 30° /7° | 0 mm | 3 | |
| Sept. 30 | Overcast | 23° /12° | 0 mm | 3 | |
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Important Notice
Our weather forecast for Great Falls in September is based on the analysis of historical data rather than real-time forecast models. While this provides a general overview, weather conditions can change. We recommend that you check the Great Falls forecast closer to your planned date for the most up-to-date weather information.
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Great Falls in September - FAQ
What are the expected maximum and minimum temperatures in Great Falls during September?
Enjoy moderate daytime temperatures of up to 26° and cooler nights around 9°. Ideal for a range of outdoor activities, from hiking to city tours.
How much rainfall should be expected in Great Falls during September?
In September, Great Falls can expect light to moderate rainfall, totaling 38.4 mm across approximately 5 days. Occasional showers are possible, and planning ahead for them could be helpful.
What are the typical wind conditions in Great Falls during September?
The average wind speed in Great Falls during September is 22 km/h, suggesting breezy to windy conditions, depending on your activities.
September rainfall patterns in Great Falls
Explore the daily rainfall trends and prepare for Great Fallss September weather 💧
Typically, Great Falls has 5 rainy days in September with a total of 38.4 mm of rainfall.
UV exposure in Great Falls during September
Stay informed about UV levels for safe outdoor activities throughout the month of September ☀️
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