S
M
T
W
T
F
S
30
80°
49°
31
82°
48°
1
81°
47°
2
81°
50°
3
80°
45°
4
74°
46°
5
74°
48°
6
75°
43°
7
73°
43°
8
73°
44°
9
74°
46°
10
74°
41°
11
75°
40°
12
73°
41°
13
73°
39°
14
72°
44°
15
74°
43°
16
73°
38°
17
70°
37°
18
71°
36°
19
72°
38°
20
72°
40°
21
75°
39°
22
70°
43°
23
74°
44°
24
73°
44°
25
Hist. Avg.
71°
39°
26
Hist. Avg.
71°
39°
27
Hist. Avg.
71°
38°
28
Hist. Avg.
70°
38°
29
Hist. Avg.
70°
37°
30
Hist. Avg.
70°
37°
1
Hist. Avg.
69°
37°
2
Hist. Avg.
69°
36°
3
Hist. Avg.
68°
36°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
*Temporarily Unavailable
September Weather in Flagstaff
Flagstaff's September 2026 forecast shows daily high temperatures ranging from 70° to 82°, with overnight lows between 36° and 50°. The average high for September is 75° with an average low of 43°. AccuWeather's monthly forecast extends further ahead than any other source, with day-by-day RealFeel® Temperatures giving a complete picture of how September weather will actually feel in Flagstaff. See also: October | November | December.
