S
M
T
W
T
F
S
26
77°
67°
27
77°
67°
28
75°
66°
29
73°
68°
30
75°
67°
31
74°
68°
1
73°
69°
2
75°
69°
3
77°
68°
4
74°
68°
5
74°
66°
6
75°
67°
7
72°
68°
8
69°
68°
9
72°
68°
10
71°
63°
11
70°
64°
12
69°
64°
13
Hist. Avg.
73°
66°
14
Hist. Avg.
73°
66°
15
Hist. Avg.
73°
66°
16
Hist. Avg.
73°
66°
17
Hist. Avg.
73°
66°
18
Hist. Avg.
73°
66°
19
Hist. Avg.
73°
66°
20
Hist. Avg.
74°
66°
21
Hist. Avg.
74°
66°
22
Hist. Avg.
74°
66°
23
Hist. Avg.
74°
66°
24
Hist. Avg.
74°
66°
25
Hist. Avg.
74°
65°
26
Hist. Avg.
74°
65°
27
Hist. Avg.
74°
65°
28
Hist. Avg.
74°
65°
29
Hist. Avg.
74°
65°
30
Hist. Avg.
74°
65°
31
Hist. Avg.
74°
65°
1
Hist. Avg.
74°
65°
2
Hist. Avg.
74°
65°
3
Hist. Avg.
74°
65°
4
Hist. Avg.
74°
65°
5
Hist. Avg.
74°
65°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
*Temporarily Unavailable
August Weather in Costa Mesa
Costa Mesa's August 2026 forecast shows daily high temperatures ranging from 69° to 77°, with overnight lows between 63° and 69°. The average high for August is 73° 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 Costa Mesa. See also: September | October | November.
