S
M
T
W
T
F
S
26
33°
24°
27
43°
23°
28
51°
27°
29
53°
28°
30
57°
29°
1
71°
31°
2
64°
36°
3
71°
36°
4
50°
31°
5
44°
23°
6
60°
43°
7
58°
40°
8
65°
45°
9
60°
40°
10
68°
44°
11
67°
46°
12
64°
43°
13
73°
44°
14
73°
44°
15
68°
42°
16
66°
39°
17
76°
49°
18
67°
42°
19
57°
40°
20
58°
40°
21
58°
36°
22
66°
42°
23
68°
45°
24
66°
45°
25
60°
41°
26
67°
46°
27
59°
44°
28
60°
42°
29
60°
38°
30
61°
42°
31
69°
45°
1
71°
48°
2
73°
49°
3
73°
49°
4
72°
50°
5
72°
49°
6
73°
50°
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 44° to 76°, with overnight lows between 23° and 50°. The average high for May is 65° with an average low of 43°. 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.
