S
M
T
W
T
F
S
26
89°
71°
27
88°
68°
28
91°
71°
29
84°
67°
30
84°
71°
31
85°
67°
1
86°
72°
2
92°
73°
3
92°
73°
4
91°
71°
5
90°
71°
6
91°
73°
7
92°
72°
8
91°
73°
9
92°
70°
10
84°
67°
11
87°
70°
12
88°
71°
13
89°
70°
14
83°
63°
15
82°
62°
16
82°
62°
17
83°
63°
18
82°
66°
19
84°
68°
20
87°
69°
21
85°
68°
22
86°
69°
23
85°
69°
24
88°
61°
25
85°
63°
26
85°
66°
27
84°
67°
28
85°
63°
29
84°
62°
30
80°
62°
31
81°
64°
1
83°
64°
2
81°
57°
3
80°
56°
4
77°
57°
5
78°
57°
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 77° to 92°, with overnight lows between 56° and 73°. The average high for August is 86° with an average low of 67°. 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.
