S
M
T
W
T
F
S
30
95°
63°
31
100°
65°
1
100°
70°
2
101°
73°
3
100°
73°
4
100°
73°
5
102°
74°
6
91°
73°
7
88°
62°
8
95°
59°
9
94°
70°
10
81°
69°
11
84°
68°
12
89°
69°
13
88°
65°
14
88°
70°
15
99°
72°
16
97°
74°
17
87°
68°
18
80°
65°
19
77°
60°
20
76°
57°
21
77°
58°
22
79°
60°
23
81°
59°
24
78°
58°
25
83°
64°
26
83°
63°
27
82°
64°
28
83°
63°
29
81°
64°
30
80°
62°
1
80°
56°
2
78°
62°
3
81°
62°
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 76° to 99°, with overnight lows between 56° and 74°. The average high for September is 83° 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.
