S
M
T
W
T
F
S
26
80°
57°
27
81°
59°
28
77°
67°
29
71°
68°
30
71°
64°
31
79°
63°
1
81°
68°
2
82°
70°
3
76°
68°
4
84°
64°
5
82°
63°
6
86°
72°
7
N/A
8
86°
71°
9
88°
66°
10
84°
70°
11
86°
66°
12
83°
64°
13
82°
65°
14
81°
63°
15
80°
62°
16
80°
61°
17
77°
62°
18
76°
61°
19
77°
63°
20
74°
61°
21
75°
62°
22
75°
65°
23
79°
67°
24
74°
61°
25
74°
64°
26
77°
65°
27
80°
66°
28
81°
65°
29
77°
60°
30
73°
58°
31
73°
58°
1
74°
59°
2
72°
62°
3
72°
60°
4
73°
62°
5
72°
63°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
*Temporarily Unavailable
August Weather in Portsmouth
Portsmouth's August 2026 forecast shows daily high temperatures ranging from 72° to 88°, with overnight lows between 58° and 71°. The average high for August is 78° with an average low of 63°. 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 Portsmouth. See also: September | October | November.
