S
M
T
W
T
F
S
30
66°
49°
31
66°
48°
1
72°
46°
2
73°
49°
3
73°
50°
4
74°
50°
5
75°
41°
6
75°
37°
7
69°
36°
8
61°
40°
9
62°
42°
10
61°
45°
11
66°
46°
12
67°
45°
13
64°
37°
14
60°
35°
15
57°
33°
16
63°
34°
17
67°
35°
18
58°
33°
19
Hist. Avg.
60°
37°
20
Hist. Avg.
60°
36°
21
Hist. Avg.
60°
36°
22
Hist. Avg.
59°
36°
23
Hist. Avg.
59°
35°
24
Hist. Avg.
58°
35°
25
Hist. Avg.
58°
35°
26
Hist. Avg.
58°
35°
27
Hist. Avg.
57°
34°
28
Hist. Avg.
57°
34°
29
Hist. Avg.
56°
34°
30
Hist. Avg.
56°
33°
1
Hist. Avg.
56°
33°
2
Hist. Avg.
55°
33°
3
Hist. Avg.
55°
32°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
*Temporarily Unavailable
September Weather in St. Louis
St. Louis's September 2026 forecast shows daily high temperatures ranging from 57° to 75°, with overnight lows between 33° and 50°. The average high for September is 66° with an average low of 42°. 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.
