S
M
T
W
T
F
S
30
95°
63°
31
100°
65°
1
100°
70°
2
101°
73°
3
99°
74°
4
100°
74°
5
98°
71°
6
93°
69°
7
93°
71°
8
97°
77°
9
99°
69°
10
94°
71°
11
84°
67°
12
86°
68°
13
88°
68°
14
85°
65°
15
82°
60°
16
84°
67°
17
84°
66°
18
79°
63°
19
80°
66°
20
83°
65°
21
83°
66°
22
81°
64°
23
81°
61°
24
80°
63°
25
81°
63°
26
80°
58°
27
72°
52°
28
71°
51°
29
69°
52°
30
73°
52°
1
70°
55°
2
75°
58°
3
69°
57°
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 69° to 101°, with overnight lows between 51° and 77°. The average high for September is 84° with an average low of 64°. 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.
