S
M
T
W
T
F
S
26
54°
25°
27
50°
34°
28
48°
28°
29
55°
27°
30
54°
28°
1
55°
25°
2
72°
34°
3
72°
37°
4
55°
34°
5
45°
28°
6
46°
27°
7
63°
23°
8
68°
32°
9
57°
36°
10
57°
30°
11
75°
32°
12
72°
48°
13
79°
37°
14
81°
54°
15
79°
48°
16
64°
45°
17
54°
43°
18
46°
41°
19
52°
36°
20
66°
32°
21
68°
48°
22
54°
46°
23
68°
50°
24
84°
48°
25
93°
57°
26
93°
59°
27
91°
68°
28
93°
63°
29
80°
62°
30
75°
61°
31
73°
61°
1
77°
56°
2
78°
61°
3
81°
60°
4
80°
57°
5
78°
56°
6
81°
60°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
May Weather in Fullerton
Fullerton's May 2026 forecast shows daily high temperatures ranging from 73° to 81°, with overnight lows between 56° and 62°. The average high for May is 78° 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 Fullerton. See also: June | July | August.
