S
M
T
W
T
F
S
26
64°
54°
27
65°
52°
28
71°
49°
29
72°
50°
30
71°
54°
1
74°
57°
2
73°
57°
3
67°
55°
4
70°
53°
5
70°
55°
6
74°
56°
7
76°
55°
8
83°
57°
9
84°
58°
10
83°
56°
11
81°
55°
12
88°
57°
13
83°
58°
14
81°
57°
15
80°
56°
16
77°
57°
17
79°
58°
18
80°
59°
19
80°
59°
20
79°
58°
21
80°
59°
22
80°
59°
23
81°
60°
24
81°
60°
25
80°
59°
26
80°
60°
27
79°
59°
28
73°
57°
29
72°
58°
30
74°
57°
31
73°
59°
1
75°
60°
2
77°
59°
3
77°
59°
4
76°
58°
5
75°
57°
6
74°
55°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
May Weather in Irvine-Lake Forest
Irvine-Lake Forest's May 2026 forecast shows daily high temperatures ranging from 67° to 88°, with overnight lows between 53° and 60°. The average high for May is 78° with an average low of 58°. 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 Irvine-Lake Forest. See also: June | July | August.
