S
M
T
W
T
F
S
26
32°
26°
27
34°
28°
28
40°
28°
29
48°
26°
30
48°
24°
1
53°
28°
2
69°
27°
3
61°
39°
4
51°
35°
5
44°
23°
6
47°
17°
7
55°
34°
8
62°
39°
9
53°
37°
10
64°
34°
11
81°
40°
12
68°
40°
13
81°
36°
14
69°
41°
15
68°
37°
16
68°
43°
17
51°
37°
18
38°
29°
19
51°
24°
20
59°
26°
21
64°
36°
22
54°
33°
23
66°
31°
24
76°
40°
25
84°
57°
26
83°
55°
27
76°
52°
28
73°
52°
29
79°
53°
30
76°
53°
31
76°
50°
1
73°
48°
2
72°
47°
3
78°
50°
4
73°
49°
5
74°
51°
6
75°
51°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
May Weather in Keystone
Keystone's May 2026 forecast shows daily high temperatures ranging from 72° to 84°, with overnight lows between 47° and 57°. The average high for May is 76° with an average low of 51°. 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 Keystone. See also: June | July | August.
