S
M
T
W
T
F
S
26
61°
35°
27
65°
40°
28
60°
48°
29
50°
35°
30
50°
31°
1
48°
29°
2
43°
27°
3
59°
26°
4
69°
41°
5
60°
44°
6
49°
37°
7
51°
32°
8
57°
33°
9
62°
35°
10
52°
32°
11
52°
31°
12
55°
28°
13
54°
40°
14
54°
40°
15
65°
47°
16
67°
49°
17
74°
56°
18
82°
65°
19
76°
54°
20
60°
34°
21
55°
39°
22
63°
41°
23
68°
50°
24
67°
47°
25
69°
50°
26
70°
52°
27
69°
50°
28
71°
45°
29
67°
50°
30
73°
46°
31
64°
41°
1
63°
42°
2
62°
42°
3
64°
43°
4
66°
47°
5
70°
53°
6
75°
54°
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 55° to 82°, with overnight lows between 34° and 65°. The average high for May is 68° with an average low of 48°. 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.
