Flathead County (Glacier National Park)
September
Weather in Flathead County, Montana for September 2025
Your guide to Flathead County weather in September - trends and predictions
In general, the average temperature in Flathead County at the beginning of September is 28.7 °F. As the month progressed, temperatures tended to significantly cool down, reaching an average of 20.3 °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 45.4 mm.
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Temperatures
Rain 🌧️
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21
Dry days
9
Rainy days
0
Snow days
22°/9°
Temperatures
12 km/h
Avg max wind
54 %
Avg humidity
Flathead County Weather September
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Temperatures trend during September in Flathead County
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September weather in Flathead County day by day
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| Date | Weather | Temperatures | Rain | UV | More |
|---|---|---|---|---|---|
| Sept. 1 |  Overcast | 30° /9° | 0 mm | 7 | |
| Sept. 2 |  Partly cloudy | 30° /11° | 0 mm | 8 | |
| Sept. 3 | Overcast | 24° /12° | 0 mm | 5 | |
| Sept. 4 |  Sunny | 27° /9° | 0 mm | 7 | |
| Sept. 5 | Sunny | 29° /9° | 0 mm | 7 | |
| Sept. 6 | Sunny | 30° /10° | 0 mm | 8 | |
| Sept. 7 | Sunny | 31° /10° | 0 mm | 8 | |
| Sept. 8 | Sunny | 31° /11° | 0 mm | 8 | |
| Sept. 9 | Sunny | 28° /13° | 0 mm | 7 | |
| Sept. 10 | Sunny | 26° /8° | 0 mm | 7 | |
| Sept. 11 |  Patchy rain possible | 20° /10° | 0.8 mm | 5 | |
| Sept. 12 |  Heavy rain at times | 14° /10° | 14.9 mm | 3 | |
| Sept. 13 | Patchy rain possible | 17° /9° | 3.1 mm | 4 | |
| Sept. 14 | Patchy rain possible | 17° /8° | 0.1 mm | 4 | |
| Sept. 15 | Patchy rain possible | 18° /6° | 0.1 mm | 4 | |
| Sept. 16 | Sunny | 21° /7° | 0 mm | 6 | |
| Sept. 17 |  Moderate or heavy rain shower | 20° /11° | 2.4 mm | 5 | |
| Sept. 18 | Overcast | 17° /11° | 20.5 mm | 4 | |
| Sept. 19 | Patchy rain possible | 21° /9° | 0.1 mm | 5 | |
| Sept. 20 | Patchy rain possible | 16° /9° | 0.3 mm | 4 | |
| Sept. 21 | Overcast | 16° /4° | 0 mm | 4 | |
| Sept. 22 | Overcast | 18° /6° | 0 mm | 4 | |
| Sept. 23 | Partly cloudy | 21° /9° | 0 mm | 6 | |
| Sept. 24 | Sunny | 23° /10° | 0 mm | 6 | |
| Sept. 25 | Patchy rain possible | 27° /13° | 0.9 mm | 6 | |
| Sept. 26 |  Cloudy | 18° /11° | 1.8 mm | 4 | |
| Sept. 27 | Cloudy | 20° /7° | 0 mm | 5 | |
| Sept. 28 | Partly cloudy | 25° /8° | 0 mm | 6 | |
| Sept. 29 | Patchy rain possible | 16° /8° | 0.4 mm | 4 | |
| Sept. 30 | Sunny | 13° /3° | 0 mm | 4 | |
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Important Notice
Our weather forecast for Flathead County 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 Flathead County forecast closer to your planned date for the most up-to-date weather information.
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Flathead County in September - FAQ
What are the expected maximum and minimum temperatures in Flathead County during September?
Enjoy moderate daytime temperatures of up to 22° and cooler nights around 9°. Ideal for a range of outdoor activities, from hiking to city tours.
How much rainfall should be expected in Flathead County during September?
In September, Flathead County can expect light to moderate rainfall, totaling 45.4 mm across approximately 9 days. Occasional showers are possible, and planning ahead for them could be helpful.
What are the typical wind conditions in Flathead County during September?
The average wind speed in Flathead County during September is 12 km/h, suggesting breezy to windy conditions, depending on your activities.
September rainfall patterns in Flathead County
Explore the daily rainfall trends and prepare for Flathead Countys September weather 💧
UV exposure in Flathead County during September
Stay informed about UV levels for safe outdoor activities throughout the month of 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.
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