S
M
T
W
T
F
S
30
87°
65°
31
86°
66°
1
88°
69°
2
88°
67°
3
85°
64°
4
84°
63°
5
84°
62°
6
85°
62°
7
85°
63°
8
86°
63°
9
88°
67°
10
88°
63°
11
87°
62°
12
89°
66°
13
88°
65°
14
88°
66°
15
87°
66°
16
87°
65°
17
88°
63°
18
87°
63°
19
86°
62°
20
85°
62°
21
84°
63°
22
82°
61°
23
81°
59°
24
80°
61°
25
80°
62°
26
Hist. Avg.
81°
58°
27
Hist. Avg.
80°
58°
28
Hist. Avg.
80°
58°
29
Hist. Avg.
80°
57°
30
Hist. Avg.
79°
57°
1
Hist. Avg.
79°
56°
2
Hist. Avg.
79°
56°
3
Hist. Avg.
78°
56°
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 80° to 89°, with overnight lows between 59° and 69°. The average high for September is 86° 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 Saint Charles. See also: October | November | December.
