S
M
T
W
T
F
S
30
87°
68°
31
86°
65°
1
83°
62°
2
87°
66°
3
87°
71°
4
90°
72°
5
81°
68°
6
73°
68°
7
80°
67°
8
84°
67°
9
79°
59°
10
79°
54°
11
84°
60°
12
72°
57°
13
70°
49°
14
62°
49°
15
70°
53°
16
75°
53°
17
68°
59°
18
63°
59°
19
62°
57°
20
68°
50°
21
55°
46°
22
61°
45°
23
61°
51°
24
65°
51°
25
68°
52°
26
68°
53°
27
69°
52°
28
69°
53°
29
66°
48°
30
69°
50°
1
70°
51°
2
67°
42°
3
63°
48°
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 55° to 70°, with overnight lows between 42° and 53°. The average high for September is 66° with an average low of 49°. 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.
