S
M
T
W
T
F
S
26
59°
38°
27
71°
35°
28
56°
39°
29
57°
47°
30
60°
41°
1
64°
34°
2
57°
41°
3
61°
38°
4
72°
36°
5
82°
50°
6
66°
49°
7
64°
39°
8
61°
45°
9
58°
48°
10
70°
47°
11
59°
37°
12
59°
38°
13
58°
44°
14
61°
45°
15
65°
47°
16
70°
50°
17
71°
48°
18
73°
53°
19
73°
53°
20
70°
50°
21
67°
46°
22
66°
47°
23
67°
47°
24
68°
48°
25
70°
51°
26
73°
52°
27
70°
50°
28
73°
49°
29
70°
47°
30
74°
52°
31
78°
57°
1
76°
57°
2
77°
52°
3
78°
57°
4
80°
59°
5
80°
58°
6
79°
59°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
May Weather in Lewistown
Lewistown's May 2026 forecast shows daily high temperatures ranging from 58° to 80°, with overnight lows between 37° and 59°. The average high for May is 70° with an average low of 49°. 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 Lewistown. See also: June | July | August.
