S
M
T
W
T
F
S
30
78°
54°
31
70°
50°
1
74°
52°
2
74°
53°
3
75°
54°
4
75°
53°
5
73°
52°
6
76°
52°
7
74°
51°
8
74°
52°
9
77°
52°
10
76°
51°
11
76°
44°
12
79°
50°
13
78°
49°
14
79°
49°
15
79°
49°
16
78°
48°
17
79°
49°
18
78°
48°
19
77°
47°
20
77°
47°
21
76°
46°
22
77°
46°
23
77°
45°
24
76°
46°
25
74°
45°
26
71°
44°
27
67°
43°
28
71°
43°
29
73°
42°
30
71°
42°
1
71°
41°
2
72°
43°
3
72°
42°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in Flagstaff
Flagstaff's September 2026 forecast shows daily high temperatures ranging from 67° to 79°, with overnight lows between 41° and 54°. The average high for September is 75° with an average low of 48°. 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.
