S
M
T
W
T
F
S
26
77°
52°
27
81°
50°
28
73°
58°
29
66°
51°
30
61°
42°
1
63°
36°
2
56°
36°
3
63°
32°
4
77°
49°
5
71°
59°
6
60°
49°
7
63°
44°
8
71°
36°
9
72°
51°
10
77°
51°
11
71°
47°
12
77°
43°
13
75°
52°
14
63°
40°
15
74°
58°
16
83°
63°
17
88°
67°
18
91°
67°
19
80°
67°
20
71°
56°
21
68°
51°
22
73°
55°
23
79°
59°
24
80°
60°
25
78°
61°
26
77°
60°
27
78°
62°
28
77°
57°
29
78°
62°
30
76°
60°
31
73°
58°
1
73°
57°
2
74°
56°
3
74°
55°
4
77°
61°
5
81°
64°
6
82°
64°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
May Weather in Mount Vernon
Mount Vernon's May 2026 forecast shows daily high temperatures ranging from 68° to 91°, with overnight lows between 51° and 67°. The average high for May is 78° with an average low of 60°. 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 Mount Vernon. See also: June | July | August.