S
M
T
W
T
F
S
26
45°
24°
27
46°
29°
28
54°
28°
29
59°
30°
30
60°
27°
1
68°
26°
2
75°
34°
3
74°
40°
4
62°
42°
5
51°
33°
6
60°
22°
7
68°
43°
8
73°
48°
9
66°
39°
10
78°
54°
11
81°
50°
12
82°
51°
13
84°
49°
14
81°
48°
15
87°
52°
16
83°
50°
17
83°
50°
18
79°
49°
19
83°
51°
20
73°
44°
21
67°
46°
22
67°
45°
23
68°
45°
24
68°
46°
25
69°
45°
26
73°
50°
27
79°
51°
28
80°
51°
29
79°
50°
30
78°
52°
31
79°
52°
1
81°
51°
2
82°
53°
3
82°
50°
4
71°
48°
5
72°
52°
6
75°
53°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
May Weather in Thermopolis
Thermopolis's May 2026 forecast shows daily high temperatures ranging from 66° to 87°, with overnight lows between 39° and 54°. The average high for May is 76° 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 Thermopolis. See also: June | July | August.