S
M
T
W
T
F
S
30
76°
54°
31
79°
55°
1
81°
57°
2
80°
58°
3
81°
59°
4
80°
52°
5
76°
51°
6
78°
58°
7
77°
55°
8
79°
56°
9
80°
55°
10
80°
56°
11
79°
56°
12
80°
55°
13
80°
56°
14
79°
56°
15
79°
55°
16
76°
55°
17
77°
51°
18
76°
45°
19
72°
42°
20
68°
45°
21
68°
45°
22
71°
40°
23
66°
42°
24
66°
51°
25
65°
52°
26
66°
52°
27
68°
51°
28
70°
51°
29
64°
52°
30
66°
45°
1
65°
39°
2
63°
38°
3
60°
37°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in St. Louis
St. Louis's September 2026 forecast shows daily high temperatures ranging from 60° to 81°, with overnight lows between 37° and 59°. The average high for September is 73° with an average low of 51°. 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. Louis. See also: October | November | December.
