S
M
T
W
T
F
S
26
65°
55°
27
65°
54°
28
67°
54°
29
68°
54°
30
69°
58°
1
69°
60°
2
66°
59°
3
67°
60°
4
67°
56°
5
66°
56°
6
68°
55°
7
67°
56°
8
68°
61°
9
68°
61°
10
68°
61°
11
67°
59°
12
69°
58°
13
68°
60°
14
71°
59°
15
70°
61°
16
70°
61°
17
69°
61°
18
69°
61°
19
69°
57°
20
76°
62°
21
70°
62°
22
68°
62°
23
69°
62°
24
68°
62°
25
68°
58°
26
67°
59°
27
67°
57°
28
68°
56°
29
66°
60°
30
69°
57°
31
71°
61°
1
71°
62°
2
70°
61°
3
69°
62°
4
69°
62°
5
70°
62°
6
71°
64°
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 ° to °, with overnight lows between ° and °. The average high for May is ° with an average low of °. 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.
