Gallatin County (Bozeman)
September
Weather in Gallatin County, Montana for September 2026
Your guide to Gallatin County weather in September - trends and predictions
Until now, September 2026 in Gallatin County is slightly cooler than the historical average by 0.7 °F.
The forecast for the next days in Gallatin County predicts temperatures to be around 20 °F, close to the historical average.
In general, the average temperature in Gallatin County at the beginning of September is 25.7 °F. As the month progressed, temperatures tended to significantly cool down, reaching an average of 19 °F by the end of September.
Gallatin County experiences moderate rainfall in September, with an average of 8 rainy days and a total precipitation of 125.1 mm.
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Temperatures
Rain 🌧️
More
22
Dry days
8
Rainy days
0
Snow days
22°/9°
Temperatures
14 km/h
Avg max wind
46 %
Avg humidity
Gallatin County Weather September
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Temperatures trend during September in Gallatin County
See the weather trend as well as the moving average line
September weather in Gallatin County day by day
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| Date | Weather | Temperatures | Rain | UV | More |
|---|---|---|---|---|---|
| Sept. 1 |  Sunny | 28° /11° | 0.4 mm | 6 | |
| Sept. 2 |  Partly cloudy | 29° /13° | 0 mm | 7 | |
| Sept. 3 |  Moderate rain at times | 25° /12° | 0.3 mm | 5 | |
| Sept. 4 |  Overcast | 24° /9° | 0 mm | 6 | |
| Sept. 5 | Sunny | 24° /6° | 0 mm | 7 | |
| Sept. 6 | Sunny | 26° /7° | 0 mm | 7 | |
| Sept. 7 | Sunny | 24° /10° | 0.7 mm | 6 | |
| Sept. 8 | Sunny | 24° /9° | 0 mm | 6 | |
| Sept. 9 | Overcast | 25° /10° | 0 mm | 7 | |
| Sept. 10 | Overcast | 28° /10° | 0 mm | 6 | |
| Sept. 11 | Moderate rain at times | 24° /10° | 0.3 mm | 5 | |
| Sept. 12 | Moderate or heavy rain shower | 18° /6° | 5.1 mm | 3 | |
| Sept. 13 | Overcast | 18° /6° | 16 mm | 4 | |
| Sept. 14 | Partly cloudy | 19° /6° | 3.6 mm | 5 | |
| Sept. 15 |  Cloudy | 19° /6° | 0 mm | 5 | |
| Sept. 16 | Overcast | 19° /7° | 14.8 mm | 5 | |
| Sept. 17 | Moderate or heavy rain shower | 20° /7° | 4.1 mm | 3 | |
| Sept. 18 | Moderate or heavy rain shower | 18° /8° | 28.5 mm | 3 | |
| Sept. 19 | Cloudy | 18° /8° | 3.2 mm | 3 | |
| Sept. 20 | Sunny | 17° /7° | 0 mm | 5 | |
| Sept. 21 | Sunny | 22° /8° | 0 mm | 5.6 | |
| Sept. 22 | Overcast | 23° /10° | 0.9 mm | 5.3 | |
| Sept. 23 | Sunny | 24° /10° | 0.1 mm | 5.2 | |
| Sept. 24 | Sunny | 26° /11° | 0 mm | 5.1 | |
| Sept. 25 | Overcast | 26° /9° | 0 mm | 7 | |
| Sept. 26 | Overcast | 15° /5° | 0 mm | 4 | |
| Sept. 27 | Overcast | 22° /6° | 0 mm | 5 | |
| Sept. 28 |  Patchy rain possible | 16° /8° | 0.7 mm | 5 | |
| Sept. 29 | Patchy rain possible | 13° /4° | 1.9 mm | 3 | |
| Sept. 30 | Sunny | 15° /2° | 0.1 mm | 4 | |
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Important Notice
Our weather forecast for Gallatin 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 Gallatin County forecast closer to your planned date for the most up-to-date weather information.
Change Month
Gallatin County in September - FAQ
What are the expected maximum and minimum temperatures in Gallatin 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 Gallatin County during September?
Significant rainfall exceeding 125.1 mm is expected in Gallatin County during September, occurring over more than 8 days. Preparing for wet conditions is recommended in your planning.
What are the typical wind conditions in Gallatin County during September?
The average wind speed in Gallatin County during September is 14 km/h, suggesting breezy to windy conditions, depending on your activities.
September rainfall patterns in Gallatin County
Explore the daily rainfall trends and prepare for Gallatin Countys September weather 💧
Typically, Gallatin County has 8 rainy days in September with a total of 125.1 mm of rainfall.
UV exposure in Gallatin County during September
Stay informed about UV levels for safe outdoor activities throughout the month of September ☀️
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Where is Gallatin County?Get accurate weather forecasts for Gallatin County, located at latitude 45.68 and longitude -111.039. Stay updated with localized weather information tailored for Gallatin County.
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