S
M
T
W
T
F
S
30
82°
66°
31
86°
68°
1
90°
66°
2
89°
62°
3
83°
62°
4
81°
60°
5
78°
57°
6
77°
58°
7
75°
54°
8
77°
59°
9
78°
62°
10
73°
61°
11
75°
62°
12
78°
61°
13
78°
62°
14
79°
62°
15
79°
61°
16
76°
60°
17
74°
61°
18
78°
61°
19
74°
60°
20
75°
60°
21
76°
61°
22
77°
61°
23
77°
59°
24
70°
58°
25
66°
56°
26
67°
57°
27
71°
57°
28
73°
56°
29
74°
58°
30
74°
58°
1
73°
57°
2
73°
58°
3
70°
57°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in St. Clair
St. Clair's September 2026 forecast shows daily high temperatures ranging from 66° to 90°, with overnight lows between 54° and 68°. The average high for September is 76° with an average low of 60°. 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 St. Clair. See also: October | November | December.
