S
M
T
W
T
F
S
26
65°
55°
27
65°
54°
28
67°
54°
29
68°
54°
30
69°
58°
1
71°
58°
2
69°
57°
3
68°
58°
4
67°
59°
5
69°
59°
6
68°
59°
7
70°
61°
8
68°
60°
9
65°
61°
10
66°
61°
11
69°
60°
12
70°
61°
13
69°
62°
14
67°
58°
15
62°
54°
16
63°
55°
17
63°
55°
18
64°
56°
19
63°
55°
20
63°
56°
21
70°
60°
22
70°
62°
23
71°
61°
24
70°
60°
25
70°
61°
26
69°
61°
27
70°
60°
28
68°
59°
29
68°
57°
30
64°
56°
31
63°
56°
1
64°
57°
2
66°
58°
3
68°
60°
4
70°
60°
5
69°
61°
6
68°
61°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
May Weather in Costa Mesa
Costa Mesa's May 2026 forecast shows daily high temperatures ranging from 62° to 71°, with overnight lows between 54° and 62°. The average high for May is 67° with an average low of 59°. AccuWeather's monthly forecast extends further ahead than any other source, with day-by-day RealFeel® Temperatures giving a complete picture of how May weather will actually feel in Costa Mesa. See also: June | July | August.
