S
M
T
W
T
F
S
30
82°
65°
31
82°
66°
1
90°
70°
2
89°
66°
3
81°
63°
4
80°
60°
5
78°
57°
6
79°
58°
7
77°
55°
8
71°
56°
9
76°
55°
10
76°
56°
11
73°
51°
12
74°
51°
13
73°
53°
14
72°
50°
15
77°
55°
16
77°
55°
17
76°
54°
18
73°
54°
19
77°
56°
20
77°
56°
21
76°
55°
22
77°
55°
23
77°
54°
24
76°
54°
25
75°
53°
26
76°
52°
27
75°
53°
28
75°
52°
29
74°
51°
30
72°
51°
1
72°
50°
2
73°
52°
3
73°
50°
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 71° to 90°, with overnight lows between 50° and 70°. The average high for September is 76° with an average low of 55°. 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.
