S
M
T
W
T
F
S
30
78°
52°
31
79°
52°
1
79°
51°
2
78°
51°
3
80°
52°
4
80°
51°
5
79°
51°
6
80°
50°
7
80°
50°
8
79°
49°
9
75°
46°
10
75°
49°
11
79°
49°
12
78°
48°
13
79°
49°
14
79°
49°
15
78°
47°
16
77°
48°
17
76°
47°
18
68°
46°
19
67°
45°
20
69°
45°
21
68°
46°
22
68°
45°
23
66°
42°
24
66°
40°
25
68°
43°
26
73°
45°
27
71°
44°
28
62°
30°
29
62°
35°
30
66°
40°
1
74°
41°
2
73°
42°
3
74°
40°
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 62° to 80°, with overnight lows between 30° and 52°. The average high for September is 74° with an average low of 46°. 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.
