S
M
T
W
T
F
S
26
77°
61°
27
77°
57°
28
82°
61°
29
88°
55°
30
79°
54°
31
77°
57°
1
77°
54°
2
81°
52°
3
88°
52°
4
79°
59°
5
75°
55°
6
72°
48°
7
N/A
8
75°
59°
9
82°
61°
10
81°
62°
11
79°
64°
12
81°
64°
13
84°
66°
14
83°
64°
15
80°
62°
16
77°
60°
17
74°
58°
18
73°
59°
19
74°
57°
20
67°
51°
21
66°
50°
22
67°
51°
23
67°
51°
24
70°
56°
25
72°
56°
26
72°
54°
27
71°
54°
28
72°
56°
29
71°
56°
30
72°
55°
31
72°
56°
1
71°
55°
2
69°
50°
3
66°
50°
4
66°
50°
5
67°
49°
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 66° to 84°, with overnight lows between 49° and 66°. The average high for August is 73° with an average low of 56°. 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.
