Flagstaff (AZ)
September
Weather in Flagstaff, Arizona for September 2026
Your guide to Flagstaff weather in September - trends and predictions
Until now, September 2026 in Flagstaff is slightly cooler than the historical average by 1.1 °F.
Expect cooler weather in the next days in Flagstaff with the forecast suggesting a temperature of 23 °F, lower than the historical average.
In general, the average temperature in Flagstaff at the beginning of September is 24.6 °F. As the month progressed, temperatures tended to noticeably cool down, reaching an average of 21.7 °F by the end of September.
Flagstaff experiences moderate rainfall in September, with an average of 10 rainy days and a total precipitation of 83.4 mm.
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Temperatures
Rain 🌧️
More
20
Dry days
10
Rainy days
0
Snow days
23°/14°
Temperatures
20 km/h
Avg max wind
45 %
Avg humidity
Flagstaff Weather September
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Temperatures trend during September in Flagstaff
See the weather trend as well as the moving average line
September weather in Flagstaff day by day
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| Date | Weather | Temperatures | Rain | UV | More |
|---|---|---|---|---|---|
| Sept. 1 |  Sunny | 24° /14° | 1.6 mm | 8 | |
| Sept. 2 | Sunny | 25° /14° | 6.5 mm | 8 | |
| Sept. 3 |  Partly cloudy | 25° /14° | 1.2 mm | 8 | |
| Sept. 4 | Partly cloudy | 25° /14° | 0.8 mm | 8 | |
| Sept. 5 | Sunny | 24° /13° | 19.6 mm | 8 | |
| Sept. 6 | Sunny | 25° /14° | 0 mm | 5 | |
| Sept. 7 |  Patchy light rain | 24° /14° | 1.1 mm | 7 | |
| Sept. 8 |  Patchy light rain with thunder | 25° /14° | 0.7 mm | 6 | |
| Sept. 9 |  Thundery outbreaks possible | 24° /15° | 0.3 mm | 6 | |
| Sept. 10 | Partly cloudy | 26° /14° | 0.8 mm | 8 | |
| Sept. 11 | Sunny | 25° /13° | 5.3 mm | 9.5 | |
| Sept. 12 | Sunny | 25° /13° | 1.3 mm | 9.7 | |
| Sept. 13 | Sunny | 23° /14° | 1.4 mm | 9.8 | |
| Sept. 14 | Sunny | 23° /13° | 0 mm | 9 | |
| Sept. 15 |  Patchy rain possible | 21° /12° | 2.1 mm | 5 | |
| Sept. 16 | Patchy rain possible | 24° /12° | 2.8 mm | 6 | |
| Sept. 17 | Sunny | 24° /14° | 1.2 mm | 6 | |
| Sept. 18 | Patchy rain possible | 25° /15° | 1.5 mm | 6 | |
| Sept. 19 | Sunny | 26° /15° | 0 mm | 7 | |
| Sept. 20 | Patchy rain possible | 23° /15° | 7.1 mm | 6 | |
| Sept. 21 | Sunny | 23° /12° | 0.9 mm | 6 | |
| Sept. 22 | Sunny | 23° /12° | 0 mm | 6 | |
| Sept. 23 |  Overcast | 19° /12° | 0 mm | 4 | |
| Sept. 24 | Sunny | 18° /9° | 0 mm | 5 | |
| Sept. 25 | Sunny | 25° /15° | 0 mm | 6 | |
| Sept. 26 | Partly cloudy | 22° /14° | 0.9 mm | 6 | |
| Sept. 27 | Partly cloudy | 21° /14° | 0 mm | 6 | |
| Sept. 28 | Partly cloudy | 22° /14° | 18.7 mm | 6 | |
| Sept. 29 |  Cloudy | 22° /14° | 0 mm | 6 | |
| Sept. 30 | Cloudy | 22° /15° | 0 mm | 5 | |
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Important Notice
Our weather forecast for Flagstaff 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 Flagstaff forecast closer to your planned date for the most up-to-date weather information.
Change Month
Flagstaff in September - FAQ
What are the expected maximum and minimum temperatures in Flagstaff during September?
Enjoy moderate daytime temperatures of up to 23° and cooler nights around 14°. Ideal for a range of outdoor activities, from hiking to city tours.
How much rainfall should be expected in Flagstaff during September?
Moderate rainfall is anticipated in Flagstaff during September, with a total of 83.4 mm spread over approximately 10 days. Considering plans for rainy days is advisable.
What are the typical wind conditions in Flagstaff during September?
The average wind speed in Flagstaff during September is 20 km/h, suggesting breezy to windy conditions, depending on your activities.
September rainfall patterns in Flagstaff
Explore the daily rainfall trends and prepare for Flagstaffs September weather 💧
Typically, Flagstaff has 10 rainy days in September with a total of 83.4 mm of rainfall.
UV exposure in Flagstaff during September
Stay informed about UV levels for safe outdoor activities throughout the month of September ☀️
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