S
M
T
W
T
F
S
26
91°
65°
27
86°
64°
28
85°
63°
29
86°
64°
30
86°
64°
31
85°
65°
1
85°
64°
2
86°
64°
3
90°
69°
4
87°
68°
5
91°
64°
6
90°
65°
7
86°
67°
8
86°
67°
9
90°
69°
10
91°
68°
11
90°
68°
12
90°
67°
13
89°
66°
14
90°
63°
15
85°
62°
16
86°
64°
17
85°
63°
18
84°
65°
19
84°
67°
20
90°
67°
21
90°
65°
22
89°
63°
23
85°
62°
24
83°
66°
25
88°
65°
26
89°
66°
27
88°
64°
28
83°
60°
29
82°
61°
30
82°
62°
31
82°
62°
1
82°
63°
2
87°
63°
3
84°
64°
4
82°
61°
5
81°
59°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
August Weather in Cornwall
Cornwall's August 2026 forecast shows daily high temperatures ranging from 81° to 91°, with overnight lows between 59° and 69°. The average high for August is 86° with an average low of 64°. 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 Cornwall. See also: September | October | November.