S
M
T
W
T
F
S
30
91°
59°
31
82°
64°
1
82°
63°
2
89°
67°
3
90°
68°
4
91°
67°
5
91°
61°
6
88°
58°
7
81°
56°
8
80°
59°
9
82°
64°
10
83°
61°
11
79°
56°
12
77°
55°
13
78°
60°
14
79°
61°
15
83°
53°
16
85°
52°
17
75°
52°
18
74°
53°
19
75°
52°
20
74°
51°
21
73°
50°
22
74°
50°
23
75°
51°
24
77°
55°
25
79°
58°
26
80°
56°
27
81°
55°
28
73°
58°
29
79°
48°
30
80°
50°
1
72°
53°
2
71°
47°
3
69°
52°
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 69° to 91°, with overnight lows between 47° and 68°. The average high for September is 80° with an average low of 56°. 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.
