S
M
T
W
T
F
S
30
95°
63°
31
100°
65°
1
100°
73°
2
99°
73°
3
99°
74°
4
100°
74°
5
95°
71°
6
95°
72°
7
93°
73°
8
92°
69°
9
90°
73°
10
88°
69°
11
86°
63°
12
83°
64°
13
84°
65°
14
82°
62°
15
82°
66°
16
84°
67°
17
84°
66°
18
85°
66°
19
85°
67°
20
84°
67°
21
84°
66°
22
83°
66°
23
84°
65°
24
84°
65°
25
83°
64°
26
83°
63°
27
84°
64°
28
83°
64°
29
82°
63°
30
82°
63°
1
81°
62°
2
81°
62°
3
80°
61°
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 80° to 100°, with overnight lows between 61° and 74°. The average high for September is 87° with an average low of 67°. 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.
