S
M
T
W
T
F
S
30
92°
74°
31
92°
73°
1
90°
72°
2
89°
74°
3
90°
73°
4
89°
74°
5
88°
73°
6
88°
72°
7
89°
72°
8
90°
73°
9
90°
72°
10
91°
71°
11
91°
73°
12
90°
73°
13
90°
72°
14
89°
71°
15
87°
70°
16
87°
72°
17
89°
71°
18
89°
72°
19
86°
72°
20
87°
70°
21
86°
71°
22
87°
70°
23
88°
71°
24
89°
67°
25
88°
67°
26
88°
69°
27
87°
69°
28
87°
69°
29
Hist. Avg.
86°
67°
30
Hist. Avg.
86°
67°
1
Hist. Avg.
86°
67°
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
*Temporarily Unavailable
September Weather in Saint Charles
Saint Charles's September 2026 forecast shows daily high temperatures ranging from 86° to 92°, with overnight lows between 67° and 74°. The average high for September is 89° 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.
