S
M
T
W
T
F
S
26
68°
52°
27
66°
50°
28
65°
49°
29
65°
49°
30
66°
50°
1
66°
49°
2
67°
48°
3
66°
48°
4
65°
47°
5
65°
47°
6
66°
48°
7
68°
53°
8
76°
53°
9
71°
55°
10
68°
51°
11
69°
49°
12
66°
48°
13
66°
50°
14
68°
49°
15
69°
51°
16
68°
50°
17
69°
56°
18
77°
54°
19
71°
51°
20
70°
52°
21
71°
58°
22
71°
59°
23
72°
61°
24
80°
62°
25
81°
62°
26
81°
61°
27
82°
63°
28
82°
62°
29
84°
62°
30
84°
62°
31
83°
59°
1
76°
56°
2
74°
60°
3
77°
63°
4
78°
64°
5
77°
64°
6
81°
63°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
May Weather in National Harbor
National Harbor's May 2026 forecast shows daily high temperatures ranging from 65° to 84°, with overnight lows between 47° and 64°. The average high for May is 72° with an average low of 55°. 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 National Harbor. See also: June | July | August.
