S
M
T
W
T
F
S
30
73°
37°
31
73°
44°
1
77°
44°
2
76°
43°
3
74°
42°
4
73°
39°
5
73°
37°
6
67°
38°
7
68°
41°
8
71°
33°
9
67°
38°
10
66°
42°
11
69°
33°
12
65°
32°
13
64°
31°
14
62°
30°
15
65°
32°
16
66°
34°
17
71°
35°
18
73°
35°
19
73°
36°
20
72°
40°
21
73°
38°
22
73°
41°
23
72°
42°
24
74°
41°
25
72°
39°
26
70°
35°
27
60°
33°
28
62°
37°
29
64°
36°
30
57°
37°
1
60°
36°
2
65°
37°
3
60°
28°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in Sun Valley
Sun Valley's September 2026 forecast shows daily high temperatures ranging from 57° to 77°, with overnight lows between 28° and 44°. The average high for September is 69° with an average low of 37°. 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 Sun Valley. See also: October | November | December.
