S
M
T
W
T
F
S
30
87°
66°
31
87°
66°
1
89°
64°
2
83°
63°
3
82°
69°
4
86°
70°
5
84°
69°
6
89°
62°
7
81°
62°
8
81°
68°
9
82°
66°
10
87°
67°
11
82°
67°
12
85°
64°
13
79°
58°
14
78°
58°
15
78°
59°
16
79°
59°
17
78°
64°
18
83°
65°
19
84°
65°
20
82°
64°
21
83°
63°
22
82°
64°
23
83°
56°
24
82°
55°
25
74°
53°
26
74°
54°
27
Hist. Avg.
77°
53°
28
Hist. Avg.
77°
53°
29
Hist. Avg.
76°
52°
30
Hist. Avg.
76°
52°
1
Hist. Avg.
76°
52°
2
Hist. Avg.
75°
51°
3
Hist. Avg.
75°
51°
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 74° to 89°, with overnight lows between 53° and 70°. The average high for September is 82° with an average low of 63°. 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.
