S
M
T
W
T
F
S
26
100°
78°
27
100°
79°
28
98°
76°
29
94°
75°
30
94°
76°
31
95°
77°
1
94°
76°
2
95°
79°
3
95°
78°
4
96°
77°
5
96°
78°
6
97°
79°
7
96°
78°
8
96°
78°
9
97°
77°
10
97°
78°
11
98°
79°
12
99°
79°
13
97°
80°
14
98°
79°
15
100°
79°
16
98°
77°
17
99°
77°
18
100°
75°
19
97°
76°
20
98°
77°
21
97°
78°
22
98°
76°
23
97°
76°
24
99°
77°
25
100°
77°
26
99°
76°
27
99°
77°
28
98°
76°
29
97°
75°
30
97°
76°
31
96°
77°
1
98°
76°
2
97°
77°
3
98°
77°
4
98°
76°
5
97°
77°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
August Weather in Alton
Alton's August 2026 forecast shows daily high temperatures ranging from 94° to 100°, with overnight lows between 75° and 80°. The average high for August is 97° with an average low of 77°. 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 Alton. See also: September | October | November.
