S
M
T
W
T
F
S
26
91°
73°
27
90°
72°
28
82°
64°
29
84°
64°
30
81°
66°
31
70°
61°
1
81°
61°
2
79°
61°
3
81°
61°
4
72°
63°
5
73°
57°
6
79°
50°
7
75°
64°
8
77°
57°
9
81°
64°
10
84°
67°
11
82°
66°
12
83°
67°
13
80°
61°
14
78°
59°
15
74°
62°
16
77°
59°
17
76°
61°
18
79°
60°
19
78°
65°
20
83°
62°
21
82°
63°
22
79°
63°
23
78°
57°
24
79°
62°
25
80°
61°
26
81°
62°
27
81°
61°
28
79°
57°
29
74°
55°
30
71°
52°
31
71°
54°
1
72°
59°
2
73°
60°
3
78°
60°
4
77°
59°
5
76°
59°
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 71° to 84°, with overnight lows between 52° and 67°. The average high for August is 78° with an average low of 60°. 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.
