S
M
T
W
T
F
S
26
90°
72°
27
90°
72°
28
89°
71°
29
87°
72°
30
88°
68°
31
83°
66°
1
82°
66°
2
83°
69°
3
84°
71°
4
83°
69°
5
84°
66°
6
86°
71°
7
89°
71°
8
87°
70°
9
86°
70°
10
86°
65°
11
85°
64°
12
85°
65°
13
84°
70°
14
89°
71°
15
88°
70°
16
90°
72°
17
91°
71°
18
90°
69°
19
89°
64°
20
83°
64°
21
82°
65°
22
82°
63°
23
83°
63°
24
82°
64°
25
83°
63°
26
84°
63°
27
84°
64°
28
83°
64°
29
84°
63°
30
81°
63°
31
84°
66°
1
86°
62°
2
87°
60°
3
80°
61°
4
81°
62°
5
82°
67°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
August Weather in National Harbor
National Harbor's August 2026 forecast shows daily high temperatures ranging from 80° to 91°, with overnight lows between 60° and 72°. The average high for August is 85° with an average low of 67°. AccuWeather's monthly forecast extends further ahead than any other source, with day-by-day RealFeel® Temperatures giving a complete picture of how August weather will actually feel in National Harbor. See also: September | October | November.
