Weather in Flathead County, Montana for September 2026
Until now, September 2026 in Flathead County has been significantly cooler than historical averages by 7.2 °F, with average temperature of 15.8 °F.
The forecast for the next days in Flathead County predicts a temperature of 17.3 °F, which is cooler than the historical average.
In general, the average temperature in Flathead County at the beginning of September is 25 °F. As the month progressed, temperatures tended to significantly cool down, reaching an average of 15.4 °F by the end of September.
Flathead County experiences moderate rainfall in September, with an average of 9 rainy days and a total precipitation of 50.6 mm.
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Flathead County Weather September
Temperatures trend during September in Flathead County
September weather in Flathead County day by day
| Date | Weather | Temperatures | Rain | UV | More |
|---|---|---|---|---|---|
| Sept. 1 |  Overcast | 30° /12° | 0 mm | 6 | |
| Sept. 2 |  Partly cloudy | 29° /10° | 4.9 mm | 6 | |
| Sept. 3 | Overcast | 23° /10° | 0.4 mm | 5 | |
| Sept. 4 |  Sunny | 21° /10° | 25.3 mm | 5 | |
| Sept. 5 | Sunny | 24° /8° | 17.9 mm | 5 | |
| Sept. 6 | Sunny | 25° /9° | 30.4 mm | 5 | |
| Sept. 7 | Sunny | 23° /10° | 107.6 mm | 5 | |
| Sept. 8 | Sunny | 22° /9° | 46.1 mm | 5 | |
| Sept. 9 | Sunny | 24° /10° | 0 mm | 6 | |
| Sept. 10 | Sunny | 24° /10° | 1.5 mm | 6 | |
| Sept. 11 |  Patchy rain possible | 20° /10° | 31.2 mm | 4 | |
| Sept. 12 | Overcast | 17° /9° | 5 mm | 3 | |
| Sept. 13 | Patchy rain possible | 18° /6° | 2.1 mm | 4 | |
| Sept. 14 | Patchy rain possible | 16° /7° | 0.9 mm | 3 | |
| Sept. 15 | Overcast | 14° /3° | 0.7 mm | 2.8 | |
| Sept. 16 | Sunny | 19° /3° | 0 mm | 4.5 | |
| Sept. 17 | Sunny | 24° /4° | 0 mm | 4.7 | |
| Sept. 18 | Sunny | 23° /7° | 0 mm | 4.4 | |
| Sept. 19 | Sunny | 21° /7° | 0 mm | 5.1 | |
| Sept. 20 | Sunny | 21° /7° | 0 mm | 6 | |
| Sept. 21 | Overcast | 20° /8° | 0 mm | 4 | |
| Sept. 22 | Patchy rain possible | 12° /4° | 2.1 mm | 3 | |
| Sept. 23 |  Mist | 15° /2° | 0 mm | 4 | |
| Sept. 24 | Overcast | 18° /4° | 0 mm | 4 | |
| Sept. 25 | Sunny | 9° /-1° | 4.1 mm | 3 | |
| Sept. 26 | Sunny | 13° /-3° | 0 mm | 4 | |
| Sept. 27 | Sunny | 15° /0° | 0 mm | 5 | |
| Sept. 28 | Sunny | 18° /2° | 0 mm | 5 | |
| Sept. 29 | Patchy rain possible | 20° /10° | 0.2 mm | 5 | |
| Sept. 30 | Sunny | 15° /7° | 11.4 mm | 4 | |
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Flathead County in September - FAQ
What are the expected maximum and minimum temperatures in Flathead County during September?
How much rainfall should be expected in Flathead County during September?
What are the typical wind conditions in Flathead County during September?
September rainfall patterns in Flathead County
UV exposure in Flathead County during September
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Where is Flathead County?Get accurate weather forecasts for Flathead County, located at latitude 48.683 and longitude -113.8. Stay updated with localized weather information tailored for Flathead County.