S
M
T
W
T
F
S
30
82°
65°
31
82°
66°
1
91°
67°
2
90°
70°
3
79°
65°
4
81°
65°
5
80°
55°
6
78°
53°
7
78°
49°
8
82°
51°
9
81°
68°
10
76°
52°
11
76°
43°
12
84°
54°
13
74°
45°
14
69°
39°
15
73°
57°
16
71°
58°
17
67°
54°
18
72°
48°
19
61°
53°
20
66°
54°
21
61°
46°
22
65°
39°
23
70°
41°
24
72°
40°
25
68°
39°
26
72°
35°
27
75°
39°
28
76°
40°
29
78°
42°
30
63°
58°
1
68°
60°
2
66°
41°
3
65°
36°
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 ° to °, with overnight lows between ° and °. The average high for September is ° with an average low of °. 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.
