S
M
T
W
T
F
S
30
102°
80°
31
85°
68°
1
95°
71°
2
96°
76°
3
96°
79°
4
98°
77°
5
96°
73°
6
97°
74°
7
95°
72°
8
94°
69°
9
96°
73°
10
93°
72°
11
92°
68°
12
89°
67°
13
90°
68°
14
90°
67°
15
86°
66°
16
87°
67°
17
91°
69°
18
90°
66°
19
89°
68°
20
86°
67°
21
83°
62°
22
83°
62°
23
85°
63°
24
85°
63°
25
86°
65°
26
90°
68°
27
87°
63°
28
80°
59°
29
80°
61°
30
82°
58°
1
79°
57°
2
80°
59°
3
81°
58°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in San Manuel
San Manuel's September 2026 forecast shows daily high temperatures ranging from 79° to 97°, with overnight lows between 57° and 74°. The average high for September is 88° with an average low of 66°. 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 San Manuel. See also: October | November | December.