S
M
T
W
T
F
S
26
82°
62°
27
78°
62°
28
77°
58°
29
77°
62°
30
81°
64°
31
83°
64°
1
82°
63°
2
79°
63°
3
84°
59°
4
82°
55°
5
77°
57°
6
79°
56°
7
77°
55°
8
76°
56°
9
75°
54°
10
77°
60°
11
79°
62°
12
81°
61°
13
81°
54°
14
77°
53°
15
76°
54°
16
79°
57°
17
76°
55°
18
75°
53°
19
76°
53°
20
78°
54°
21
78°
58°
22
80°
60°
23
82°
61°
24
83°
61°
25
83°
60°
26
84°
58°
27
80°
56°
28
81°
59°
29
81°
55°
30
78°
51°
31
74°
48°
1
71°
51°
2
72°
49°
3
72°
50°
4
73°
49°
5
70°
49°
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 70° to 84°, with overnight lows between 48° and 64°. The average high for August is 78° with an average low of 57°. 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.
