S
M
T
W
T
F
S
26
89°
68°
27
88°
69°
28
90°
68°
29
87°
69°
30
88°
68°
31
86°
68°
1
83°
63°
2
83°
66°
3
82°
67°
4
84°
67°
5
88°
66°
6
89°
69°
7
89°
69°
8
88°
68°
9
88°
68°
10
87°
67°
11
88°
67°
12
87°
66°
13
88°
68°
14
90°
66°
15
86°
66°
16
88°
63°
17
82°
62°
18
83°
58°
19
80°
56°
20
80°
54°
21
79°
56°
22
79°
56°
23
81°
55°
24
81°
63°
25
84°
61°
26
88°
64°
27
87°
64°
28
89°
63°
29
88°
55°
30
83°
56°
31
76°
58°
1
78°
54°
2
77°
52°
3
77°
58°
4
84°
61°
5
83°
60°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
August Weather in St. Charles
St. Charles's August 2026 forecast shows daily high temperatures ranging from 76° to 90°, with overnight lows between 52° and 69°. The average high for August is 85° with an average low of 63°. AccuWeather's monthly forecast extends further ahead than any other source, with day-by-day RealFeel® Temperatures giving a complete picture of how August weather will actually feel in St. Charles. See also: September | October | November.
