S
M
T
W
T
F
S
30
93°
73°
31
92°
74°
1
92°
73°
2
91°
73°
3
92°
72°
4
92°
73°
5
90°
71°
6
91°
72°
7
90°
74°
8
89°
73°
9
88°
73°
10
89°
72°
11
89°
72°
12
90°
73°
13
87°
72°
14
86°
72°
15
86°
71°
16
87°
72°
17
86°
72°
18
86°
71°
19
87°
68°
20
86°
66°
21
84°
68°
22
86°
70°
23
87°
70°
24
85°
69°
25
87°
70°
26
88°
69°
27
88°
69°
28
87°
68°
29
87°
68°
30
87°
69°
1
87°
68°
2
Hist. Avg.
86°
66°
3
Hist. Avg.
86°
66°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in Saint Charles
Saint Charles's September 2026 forecast shows daily high temperatures ranging from 84° to 93°, with overnight lows between 66° and 74°. The average high for September is 88° with an average low of 71°. 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 Saint Charles. See also: October | November | December.
