S
M
T
W
T
F
S
26
92°
74°
27
93°
73°
28
94°
74°
29
94°
74°
30
93°
73°
31
91°
73°
1
91°
74°
2
93°
74°
3
93°
73°
4
92°
74°
5
93°
73°
6
92°
74°
7
88°
66°
8
89°
68°
9
90°
65°
10
86°
64°
11
84°
64°
12
85°
66°
13
85°
68°
14
84°
66°
15
84°
70°
16
90°
69°
17
86°
65°
18
86°
64°
19
83°
63°
20
83°
63°
21
84°
62°
22
84°
63°
23
89°
67°
24
90°
68°
25
91°
67°
26
90°
68°
27
89°
61°
28
88°
62°
29
83°
63°
30
82°
61°
31
81°
59°
1
82°
60°
2
81°
58°
3
80°
57°
4
80°
58°
5
81°
62°
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 80° to 94°, with overnight lows between 57° and 74°. The average high for August is 87° 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.
