S
M
T
W
T
F
S
30
92°
70°
31
90°
69°
1
83°
67°
2
85°
63°
3
81°
62°
4
82°
66°
5
83°
69°
6
88°
67°
7
89°
68°
8
82°
67°
9
86°
67°
10
87°
60°
11
79°
60°
12
79°
59°
13
80°
60°
14
80°
65°
15
85°
66°
16
82°
65°
17
84°
65°
18
77°
57°
19
76°
56°
20
75°
59°
21
75°
60°
22
78°
62°
23
82°
63°
24
81°
64°
25
82°
55°
26
81°
54°
27
74°
55°
28
72°
54°
29
72°
54°
30
73°
60°
1
70°
53°
2
72°
51°
3
Hist. Avg.
75°
51°
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 70° to 92°, with overnight lows between 51° and 70°. The average high for September is 81° with an average low of 62°. 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.
