S
M
T
W
T
F
S
26
66°
28°
27
68°
30°
28
68°
32°
29
51°
36°
30
55°
41°
1
51°
34°
2
52°
28°
3
41°
33°
4
57°
33°
5
80°
39°
6
57°
48°
7
59°
32°
8
54°
30°
9
60°
28°
10
59°
43°
11
60°
37°
12
52°
27°
13
60°
29°
14
64°
43°
15
67°
45°
16
78°
43°
17
71°
40°
18
66°
35°
19
84°
49°
20
86°
50°
21
57°
29°
22
65°
28°
23
66°
27°
24
70°
38°
25
57°
48°
26
77°
55°
27
71°
46°
28
54°
41°
29
54°
38°
30
59°
38°
31
67°
42°
1
63°
38°
2
69°
47°
3
75°
47°
4
75°
51°
5
73°
49°
6
70°
49°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
May Weather in Monticello
Monticello's May 2026 forecast shows daily high temperatures ranging from 54° to 77°, with overnight lows between 38° and 55°. The average high for May is 66° with an average low of 45°. 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 Monticello. See also: June | July | August.