S
M
T
W
T
F
S
30
85°
66°
31
89°
66°
1
87°
65°
2
89°
65°
3
89°
64°
4
88°
65°
5
83°
65°
6
88°
64°
7
85°
61°
8
81°
59°
9
80°
63°
10
79°
64°
11
86°
63°
12
86°
64°
13
87°
63°
14
86°
62°
15
85°
61°
16
77°
59°
17
79°
53°
18
76°
54°
19
77°
50°
20
75°
51°
21
74°
51°
22
75°
57°
23
76°
57°
24
82°
58°
25
81°
58°
26
80°
57°
27
81°
58°
28
80°
54°
29
79°
53°
30
78°
52°
1
76°
51°
2
78°
54°
3
72°
46°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in St. Peters
St. Peters's September 2026 forecast shows daily high temperatures ranging from 72° to 89°, with overnight lows between 46° and 66°. The average high for September is 81° with an average low of 59°. 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. Peters. See also: October | November | December.
