S
M
T
W
T
F
S
26
61°
31°
27
63°
34°
28
57°
32°
29
44°
39°
30
46°
41°
1
59°
36°
2
50°
30°
3
45°
39°
4
59°
36°
5
58°
45°
6
55°
49°
7
60°
39°
8
57°
38°
9
58°
31°
10
55°
47°
11
61°
45°
12
56°
40°
13
55°
40°
14
64°
46°
15
60°
51°
16
69°
48°
17
80°
52°
18
62°
48°
19
77°
45°
20
87°
55°
21
64°
46°
22
67°
35°
23
64°
38°
24
60°
48°
25
60°
46°
26
78°
56°
27
78°
49°
28
67°
46°
29
62°
46°
30
63°
42°
31
64°
46°
1
67°
47°
2
66°
46°
3
67°
49°
4
71°
51°
5
70°
49°
6
72°
50°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
May Weather in Sullivan
Sullivan's May 2026 forecast shows daily high temperatures ranging from 60° to 78°, with overnight lows between 38° and 56°. The average high for May is 67° with an average low of 47°. 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 Sullivan. See also: June | July | August.