Flagstaff weather in September: Flagstaff, Arizona: normal highs, lows, rain and records for September
Flagstaff in September has a normal high of 74°F and a normal low of 43°F, a daily mean of 58°F, falling from 78°F on the 1st to 70°F by the 30th. Measurable precipitation falls on 8 days in a normal September, 1.84 inches in all. (NOAA 1991-2020 normals)
In metric: a normal high of 23°C and low of 6°C, 47 mm of precipitation in September.
- NOAA stationFlagstaff Airport
- Station IDUSW00003103
- Location35.14°N 111.67°W
- Elevation7,003 ft (2,135 m)
- Population77,539
- Jan 43° 18°
- Feb 46° 20°
- Mar 52° 24°
- Apr 59° 28°
- May 68° 35°
- Jun 79° 43°
- Jul 82° 51°
- Aug 79° 51°
- Sep 74° 43°
- Oct 64° 32°
- Nov 52° 23°
- Dec 43° 17°
Each month: normal high (large) and low, °F. Fill: the month's normal mean, colder blue to hotter red.
How warm is Flagstaff in September?
The normal high is 74°F and the normal low 43°F, for a daily mean of 58.3°F. September is 6.6°F cooler than August and 10.7°F warmer than October. September is the 4th warmest month of the year in Flagstaff and the 7th wettest. Across the month the normal high falls 8°F, from 78°F on September 1 to 70°F on September 30. From one year to the next September's mean temperature typically moves about 1.6°F either way (NOAA's standard deviation), so roughly two Septembers in three average between 57°F and 60°F.
Bars above: each day's normal high to low. Columns below: the chance of 0.01 inch or more of precipitation that day, on a scale of 0 to 100% (highest 36%).
| Day | High | Low | Chance of 0.01 in | Chance of 0.10 in |
|---|---|---|---|---|
| September 1 | 78°F | 47°F | 36% | 20% |
| September 8 | 76°F | 45°F | 31% | 17% |
| September 15 | 75°F | 43°F | 26% | 15% |
| September 22 | 72°F | 40°F | 21% | 12% |
| September 30 | 70°F | 37°F | 18% | 10% |
Every day of September: normal high, low and chance of precipitation (warmest afternoon September 1, coldest night September 30)
| Day | High | Low | Chance of 0.01 in | Chance of 0.10 in | Daylight |
|---|---|---|---|---|---|
| September 1 | 78°F | 47°F | 36% | 20% | 13 h |
| September 2 | 78°F | 47°F | 35% | 19% | 12 h 50 min |
| September 3 | 77°F | 47°F | 34% | 19% | 12 h 50 min |
| September 4 | 77°F | 47°F | 34% | 19% | 12 h 50 min |
| September 5 | 77°F | 46°F | 33% | 18% | 12 h 50 min |
| September 6 | 77°F | 46°F | 32% | 18% | 12 h 50 min |
| September 7 | 77°F | 46°F | 32% | 18% | 12 h 40 min |
| September 8 | 76°F | 45°F | 31% | 17% | 12 h 40 min |
| September 9 | 76°F | 45°F | 30% | 17% | 12 h 40 min |
| September 10 | 76°F | 45°F | 30% | 17% | 12 h 40 min |
| September 11 | 76°F | 44°F | 29% | 16% | 12 h 40 min |
| September 12 | 75°F | 44°F | 28% | 16% | 12 h 30 min |
| September 13 | 75°F | 44°F | 27% | 15% | 12 h 30 min |
| September 14 | 75°F | 43°F | 27% | 15% | 12 h 30 min |
| September 15 | 75°F | 43°F | 26% | 15% | 12 h 30 min |
| September 16 | 74°F | 43°F | 25% | 14% | 12 h 20 min |
| September 17 | 74°F | 42°F | 25% | 14% | 12 h 20 min |
| September 18 | 74°F | 42°F | 24% | 13% | 12 h 20 min |
| September 19 | 73°F | 41°F | 23% | 13% | 12 h 20 min |
| September 20 | 73°F | 41°F | 23% | 13% | 12 h 20 min |
| September 21 | 73°F | 41°F | 22% | 12% | 12 h 10 min |
| September 22 | 72°F | 40°F | 21% | 12% | 12 h 10 min |
| September 23 | 72°F | 40°F | 21% | 12% | 12 h 10 min |
| September 24 | 72°F | 39°F | 20% | 11% | 12 h 10 min |
| September 25 | 71°F | 39°F | 20% | 11% | 12 h 10 min |
| September 26 | 71°F | 39°F | 20% | 11% | 12 h |
| September 27 | 71°F | 38°F | 19% | 11% | 12 h |
| September 28 | 70°F | 38°F | 19% | 10% | 12 h |
| September 29 | 70°F | 37°F | 19% | 10% | 12 h |
| September 30 | 70°F | 37°F | 18% | 10% | 11 h 50 min |
- Normal high
- 74°FSeptember average
- Normal low
- 43°FSeptember average
- Precipitation
- 1.84 inmonth total
- Days with precipitation
- 80.01 inch or more
- Nights at 32°F or colder
- 2
- Daylight
- 13 h to 11 h 50 minSeptember 1 to September 30
- Days at 70°F or more
- 24
- Days at 80°F or more
- 5
- Sunshine
- 89%of clear-sky sunlight (NASA)
Source: NOAA NCEI 1991-2020 daily normals, station USW00003103; monthly normals. Daylight is computed from the place's latitude with NOAA's solar equations.
Does it rain in Flagstaff in September?
On a given September day the chance of 0.01 inch or more is 26% on average, highest around September 1 (36%). In all, 1.84 in falls on 8 days of a normal September, 1 of them with an inch or more.
In a normal September in Flagstaff, 2 nights fall to freezing.
Source: NOAA NCEI 1991-2020 daily and monthly normals, station USW00003103.
What are the records for September in Flagstaff?
The warmest September temperature on Flagstaff's official record (since 1898) is 91°F, on September 3, 1948; the coldest is 20°F, on September 22, 1912. The wettest September brought 6.75 in (1983); the snowiest, 2.0 inches (1965).
The September mean against the 1991-2020 normal of 58.3°F: 2021 60.2°F (+1.9), 2022 61.8°F (+3.5), 2023 58.9°F (+0.6), 2024 60.9°F (+2.6), 2025 58.8°F (+0.5), 2026 60.8°F (+2.5). 6 of 6 ran warmer than normal.
| September | Mean | Against normal | Precip. |
|---|---|---|---|
| 2021 | 60.2°F | +1.9°F | 1.13 in |
| 2022 | 61.8°F | +3.5°F | 1.35 in |
| 2023 | 58.9°F | +0.6°F | 0.29 in |
| 2024 | 60.9°F | +2.6°F | 0.29 in |
| 2025 | 58.8°F | +0.5°F | 1.90 in |
| 2026 | 60.8°F | +2.5°F | 3.50 in |
Source: records: ACIS, NWS threaded record FLGthr; recent months: ACIS, station USW00003103. Records and recent months use complete months only.
How does September in Flagstaff compare across Arizona?
Across the 97 places PlainClimate covers in Arizona, September normal highs run from 70°F in Greer to 104°F in Tacna; Flagstaff's is 74°F.
Source: NOAA NCEI 1991-2020 monthly normals for every station in the state.