S
M
T
W
T
F
S
26
83°
67°
27
79°
64°
28
79°
62°
29
80°
63°
30
85°
68°
31
86°
67°
1
83°
64°
2
84°
66°
3
87°
60°
4
80°
60°
5
81°
63°
6
80°
60°
7
79°
59°
8
80°
58°
9
80°
58°
10
81°
66°
11
82°
63°
12
82°
63°
13
85°
58°
14
79°
58°
15
81°
59°
16
80°
59°
17
77°
60°
18
78°
58°
19
78°
57°
20
80°
60°
21
82°
64°
22
82°
65°
23
85°
66°
24
86°
66°
25
86°
62°
26
85°
59°
27
81°
63°
28
84°
64°
29
81°
56°
30
81°
55°
31
77°
54°
1
75°
56°
2
75°
55°
3
77°
55°
4
76°
54°
5
74°
54°
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 74° to 87°, with overnight lows between 54° and 68°. The average high for August is 81° with an average low of 61°. 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.
