Click on a day for an hourly weather forecast
The temperatures in Flagstaff in September are comfortable with low of 13°C and and high up to 24°C.
You can expect about 3 to 8 days of rain in Flagstaff during the month of September. It’s a good idea to bring along your umbrella so that you don’t get caught in poor weather.
Our weather forecast can give you a great sense of what weather to expect in Flagstaff in September 2025.
If you’re planning to visit Flagstaff in the near future, we highly recommend that you review the 14 day weather forecast for Flagstaff before you arrive.
| Month | Temperatures | Rainy Days | Dry Days | Snowy Days | Rainfall | Weather | More details |
|---|---|---|---|---|---|---|---|
| January | 6° / -3° | 3 | 20 | 8 | 49 mm | Awful | Flagstaff in January |
| February | 7° / -2° | 2 | 19 | 7 | 47 mm | Bad | Flagstaff in February |
| March | 11° / 1° | 2 | 23 | 6 | 43 mm | Bad | Flagstaff in March |
| April | 16° / 4° | 2 | 25 | 3 | 22 mm | Ok | Flagstaff in April |
| May | 20° / 7° | 3 | 27 | 1 | 24 mm | Good | Flagstaff in May |
| June | 27° / 13° | 1 | 29 | 0 | 15 mm | Perfect | Flagstaff in June |
| July | 28° / 16° | 9 | 22 | 0 | 178 mm | Good | Flagstaff in July |
| August | 27° / 16° | 6 | 25 | 0 | 127 mm | Perfect | Flagstaff in August |
| September | 24° / 13° | 4 | 26 | 0 | 56 mm | Perfect | Flagstaff in September |
| October | 18° / 6° | 3 | 28 | 1 | 30 mm | Good | Flagstaff in October |
| November | 12° / 1° | 2 | 25 | 4 | 36 mm | Bad | Flagstaff in November |
| December | 6° / -3° | 3 | 19 | 9 | 57 mm | Awful | Flagstaff in December |