S
M
T
W
T
F
S
26
62°
48°
27
65°
45°
28
54°
39°
29
61°
42°
30
66°
46°
1
68°
49°
2
62°
47°
3
59°
43°
4
58°
45°
5
60°
45°
6
58°
43°
7
56°
44°
8
58°
43°
9
53°
41°
10
54°
43°
11
58°
43°
12
55°
42°
13
54°
46°
14
55°
48°
15
58°
48°
16
60°
47°
17
57°
43°
18
60°
49°
19
63°
50°
20
63°
50°
21
62°
51°
22
64°
50°
23
64°
49°
24
63°
50°
25
62°
50°
26
59°
49°
27
58°
46°
28
58°
48°
29
59°
46°
30
61°
50°
31
64°
51°
1
64°
51°
2
65°
50°
3
65°
51°
4
63°
50°
5
62°
50°
6
60°
49°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
May Weather in Alton
Alton's May 2026 forecast shows daily high temperatures ranging from 53° to 68°, with overnight lows between 39° and 51°. The average high for May is 60° with an average low of 47°. AccuWeather's monthly forecast extends further ahead than any other source, with day-by-day RealFeel® Temperatures giving a complete picture of how May weather will actually feel in Alton. See also: June | July | August.
