Flagstaff, AZ weather in September
In September, Flagstaff sees highs around 74°F and lows around 43°F: mild, with some rain. Rain falls on about 8 days. Great for outdoor plans.
- Normal high
- 74°F
- Normal low
- 43°F
- Wet days
- 8
- 1.8 in total
- Daylight
- 12.4 h
How September changes from start to finish
| September 1 | September 30 | |
|---|---|---|
| Normal high | 78°F | 70°F |
| Normal low | 47°F | 37°F |
| Chance of a wet day | 34% | 19% |
| Sunrise / sunset | 5:59 am / 6:54 pm | 6:20 am / 6:12 pm |
| Daylight | 12.9 h | 11.9 h |
Chance of a wet day: average for the first and last 7 days of the month. Times are local clock time (Arizona time (no daylight saving)).
A typical September day
- 6 am43°Fdew point 35°F
- 9 am66°Fdew point 40°F
- Noon73°Fdew point 37°F
- 3 pm74°Fdew point 35°F
- 6 pm70°Fdew point 35°F
- 9 pm54°Fdew point 37°F
NOAA hourly normals (local standard time) from Grand Canyon NP Airport (59 mi away); average wind 6 mph.
What kind of days to expect
- Comfortable dayshigh 65-80°F (temperature only: no humidity station nearby)24 of 30
- Hot dayshigh 90°F or more0 of 30
- Wet daysat least 0.01 in of rain or melted snow8 of 30
- Notable rainat least 0.10 in4 of 30
- Freezing nightslow 32°F or below2 of 30
- Snow on the groundsnow depth 1 in or more0 of 30
Average days per September, counted from daily records for each year 1991-2020.
Rain in September
Normal precipitation is 1.8 in; a dry September brings about 0.7 in and a wet one about 3.0 in (25th and 75th percentiles). About 1 day brings half an inch or more, and about 1 an inch or more. Snow is very rare.
How September varies from year to year
- Warmest September, 1991-20202020: average high 79°F
- Coolest September1996: average high 69°F
- Wettest September1999: 4.5 in
- Driest September1992: no measurable precipitation
- Highest reading91°F (September 6, 2020)
- Lowest reading24°F (September 25, 2017)
From the station's daily records with NOAA quality flags removed; most recent date shown when a reading repeats.
September compared with August and October
| August | September | October | |
|---|---|---|---|
| Normal high | 79°F | 74°F | 64°F |
| Normal low | 51°F | 43°F | 32°F |
| Wet days | 13 | 8 | 5 |
| Comfortable days | 17 | 24 | 16 |
| Daylight | 13.4 h | 12.4 h | 11.3 h |
Highs change by -5°F from August and -10°F into October.
Nearby alternatives in September
- Warmer: Sedona, AZ24 mi · high 89°F · 5 wet days
- Drier: Peoria, AZ117 mi · high 98°F · 2 wet days
How Flagstaff ranks in September
- Normal high298th warmest of 378 cities; 13th of 13 in Arizona
- Wet days174th driest of 378
What to pack for Flagstaff in September
- Layers – afternoons near 74°F but nights near 43°F
Frost in September
The first fall frost typically comes around Sep 28; in 1 year in 10 it comes before Sep 16. All frost dates for Flagstaff.
Heating and cooling
September has 205 heating degree days and 4 cooling degree days (base 65°F), 3% of the year's total heating and cooling demand.
Questions
How hot is Flagstaff in September?
The normal high is 74°F and the normal low is 43°F. From 1991 to 2020 the hottest September reading was 91°F (September 6, 2020).
Does it rain a lot in Flagstaff in September?
About 8 days in September have at least 0.01 in of precipitation, and the normal total is 1.8 in. The wettest September in 1991-2020 was in 1999 (4.5 in); the driest was in 1992, with no measurable precipitation.
Is September a good time to visit Flagstaff?
September ranks 2nd of 12 months on our comfort score for Flagstaff (82 out of 100). It has about 24 comfortable days (judged by temperature only). The best months are May and September.
Where the numbers come from
- Temperature, rain, snowfall and frost dates: Flagstaff Pulliam Airport (USW00003103), 3.8 mi SSW of the city center, 7,003 ft (103 ft higher than the city). NOAA normals and daily records, 1991-2020.
- Snow depth: Sunset Crater Nm (USC00028329), 13 mi NNE of the city center, 6,980 ft (80 ft higher than the city). NOAA normals and daily records, 1991-2020.
- Humidity and wind by hour: Grand Canyon NP Airport (USW00003195), 59 mi NNW of the city center, 6,606 ft (294 ft lower than the city). NOAA normals and daily records, 1991-2020.
- Not available for this location: cloud cover and daily humidity and wind (no station close enough or similar enough in elevation).