S
M
T
W
T
F
S
26
58°
44°
27
70°
37°
28
63°
49°
29
64°
51°
30
66°
44°
1
62°
45°
2
58°
40°
3
62°
41°
4
70°
51°
5
73°
49°
6
76°
58°
7
75°
50°
8
66°
46°
9
65°
48°
10
69°
49°
11
73°
48°
12
72°
51°
13
66°
50°
14
68°
55°
15
68°
54°
16
69°
52°
17
68°
56°
18
69°
58°
19
78°
58°
20
77°
57°
21
75°
59°
22
78°
59°
23
79°
58°
24
79°
59°
25
74°
56°
26
72°
59°
27
72°
60°
28
80°
61°
29
77°
60°
30
79°
60°
31
77°
61°
1
75°
55°
2
72°
54°
3
72°
54°
4
73°
55°
5
73°
55°
6
74°
56°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
May Weather in Herndon
Herndon's May 2026 forecast shows daily high temperatures ranging from 58° to 80°, with overnight lows between 40° and 61°. The average high for May is 72° with an average low of 54°. 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 Herndon. See also: June | July | August.
