S
M
T
W
T
F
S
30
73°
41°
31
75°
40°
1
77°
43°
2
80°
47°
3
81°
39°
4
79°
34°
5
67°
35°
6
68°
42°
7
73°
40°
8
74°
37°
9
69°
39°
10
70°
38°
11
70°
35°
12
71°
33°
13
69°
38°
14
74°
32°
15
67°
30°
16
62°
29°
17
61°
28°
18
61°
30°
19
62°
31°
20
65°
32°
21
71°
38°
22
72°
36°
23
62°
30°
24
61°
31°
25
60°
30°
26
59°
29°
27
59°
29°
28
58°
30°
29
59°
29°
30
67°
28°
1
69°
38°
2
68°
39°
3
Hist. Avg.
63°
31°
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 58° to 81°, with overnight lows between 28° and 47°. The average high for September is 68° with an average low of 35°. 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.
