S
M
T
W
T
F
S
30
86°
65°
31
89°
64°
1
90°
62°
2
85°
58°
3
85°
59°
4
86°
62°
5
86°
61°
6
87°
63°
7
88°
59°
8
85°
59°
9
85°
56°
10
86°
57°
11
85°
58°
12
86°
61°
13
87°
58°
14
88°
57°
15
85°
64°
16
85°
63°
17
83°
64°
18
83°
63°
19
84°
63°
20
82°
62°
21
83°
63°
22
86°
63°
23
86°
62°
24
85°
63°
25
89°
62°
26
88°
61°
27
87°
59°
28
85°
58°
29
85°
60°
30
84°
61°
1
86°
62°
2
88°
61°
3
87°
57°
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 82° to 90°, with overnight lows between 56° and 65°. The average high for September is 86° with an average low of 61°. 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.
