S
M
T
W
T
F
S
26
66°
57°
27
69°
51°
28
68°
51°
29
71°
52°
30
72°
53°
31
71°
56°
1
72°
55°
2
68°
56°
3
68°
56°
4
68°
57°
5
68°
55°
6
68°
56°
7
69°
55°
8
68°
55°
9
68°
56°
10
68°
52°
11
67°
52°
12
68°
53°
13
70°
51°
14
68°
54°
15
71°
52°
16
71°
51°
17
72°
52°
18
72°
54°
19
71°
54°
20
72°
56°
21
72°
55°
22
71°
54°
23
71°
53°
24
72°
55°
25
71°
55°
26
71°
54°
27
70°
55°
28
71°
52°
29
66°
54°
30
68°
51°
31
67°
50°
1
68°
52°
2
69°
52°
3
67°
53°
4
68°
53°
5
64°
51°
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 64° to 72°, with overnight lows between 50° and 57°. The average high for August is 69° with an average low of 54°. 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.
