Flathead County (Glacier National Park)
September
Weather in Flathead County, Montana for September 2026
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 °C. As the month progressed, temperatures tended to significantly cool down, reaching an average of 21.3 °C 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.
New! Chat with our AI weatherman - it’s amazing and free.
Temperatures
Rain 🌧️
More
21
Dry days
9
Rainy days
0
Snow days
23°/10°
Temperatures
12 km/h
Avg max wind
53 %
Avg humidity
Flathead County Weather September
Move between months or click on a day
Temperatures trend during September in Flathead County
See the weather trend as well as the moving average line
September weather in Flathead County day by day
Click on a date for more information
| Date | Weather | Temperatures | Rain | UV | More |
|---|---|---|---|---|---|
| Sept. 1 |  Overcast | 32° /13° | 0 mm | 8 | |
| Sept. 2 |  Partly cloudy | 31° /13° | 0 mm | 8 | |
| Sept. 3 | Overcast | 28° /13° | 0 mm | 7 | |
| Sept. 4 |  Sunny | 25° /12° | 0 mm | 7 | |
| Sept. 5 | Sunny | 27° /9° | 0 mm | 7 | |
| Sept. 6 | Sunny | 29° /10° | 0 mm | 8 | |
| Sept. 7 | Sunny | 29° /13° | 0 mm | 7 | |
| Sept. 8 | Sunny | 28° /11° | 0 mm | 7 | |
| Sept. 9 | Sunny | 28° /12° | 0 mm | 7 | |
| Sept. 10 | Sunny | 26° /10° | 1.8 mm | 7 | |
| Sept. 11 |  Patchy rain possible | 23° /12° | 3.9 mm | 6 | |
| Sept. 12 |  Heavy rain at times | 17° /11° | 7.4 mm | 4 | |
| Sept. 13 | Patchy rain possible | 21° /7° | 1.5 mm | 5 | |
| Sept. 14 | Patchy rain possible | 21° /9° | 0.1 mm | 5 | |
| Sept. 15 | Patchy rain possible | 17° /9° | 7.2 mm | 4 | |
| Sept. 16 | Sunny | 23° /8° | 0 mm | 6 | |
| Sept. 17 |  Moderate or heavy rain shower | 23° /12° | 1.2 mm | 6 | |
| Sept. 18 | Overcast | 22° /11° | 10.3 mm | 6 | |
| Sept. 19 | Patchy rain possible | 24° /10° | 0.1 mm | 6 | |
| Sept. 20 | Patchy rain possible | 21° /11° | 0.2 mm | 6 | |
| Sept. 21 | Overcast | 16° /8° | 4.1 mm | 4 | |
| Sept. 22 | Overcast | 18° /6° | 0 mm | 4 | |
| Sept. 23 | Partly cloudy | 23° /8° | 0 mm | 6 | |
| Sept. 24 | Sunny | 24° /10° | 0 mm | 7 | |
| Sept. 25 | Patchy rain possible | 27° /12° | 0.4 mm | 7 | |
| Sept. 26 |  Cloudy | 19° /11° | 0.9 mm | 5 | |
| Sept. 27 | Cloudy | 20° /6° | 0 mm | 6 | |
| Sept. 28 | Partly cloudy | 24° /9° | 0 mm | 6 | |
| Sept. 29 | Patchy rain possible | 20° /10° | 0.2 mm | 5 | |
| Sept. 30 | Sunny | 15° /7° | 11.4 mm | 4 | |
| Next | |||||
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.
Change Month
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 23° and cooler nights around 10°. Ideal for a range of outdoor activities, from hiking to city tours.
How much rainfall should be expected in Flathead County during September?
Moderate rainfall is anticipated in Flathead County during September, with a total of 50.6 mm spread over approximately 9 days. Considering plans for rainy days is advisable.
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 💧
Typically, Flathead County has 9 rainy days in September with a total of 50.6 mm of rainfall.
UV exposure in Flathead County during September
Stay informed about UV levels for safe outdoor activities throughout the month of September ☀️
Top locations in Flathead County
Select a location for an accurate weather forecast
More Locations Quick links
More Flathead County weather pages
You are here
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.
Found a mistake?
We appreciate your attention to details. Tell us here.