S
M
T
W
T
F
S
30
97°
62°
31
94°
63°
1
97°
62°
2
97°
62°
3
96°
61°
4
94°
58°
5
92°
56°
6
91°
58°
7
90°
55°
8
88°
56°
9
89°
57°
10
90°
59°
11
92°
61°
12
95°
60°
13
95°
60°
14
94°
57°
15
92°
56°
16
90°
60°
17
90°
62°
18
93°
62°
19
93°
61°
20
94°
62°
21
94°
61°
22
89°
60°
23
89°
56°
24
87°
55°
25
86°
54°
26
84°
55°
27
83°
58°
28
87°
56°
29
86°
56°
30
90°
58°
1
84°
57°
2
85°
56°
3
Hist. Avg.
85°
55°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in Simi Valley
Simi Valley's September 2026 forecast shows daily high temperatures ranging from 83° to 97°, with overnight lows between 54° and 63°. The average high for September is 91° with an average low of 59°. 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 Simi Valley. See also: October | November | December.
