S
M
T
W
T
F
S
26
67°
57°
27
68°
56°
28
68°
54°
29
69°
53°
30
69°
59°
1
69°
59°
2
70°
60°
3
69°
60°
4
68°
55°
5
69°
56°
6
70°
55°
7
72°
59°
8
73°
58°
9
72°
59°
10
71°
58°
11
70°
59°
12
70°
59°
13
68°
60°
14
70°
59°
15
69°
58°
16
70°
60°
17
72°
61°
18
72°
62°
19
73°
62°
20
73°
61°
21
72°
62°
22
73°
62°
23
73°
63°
24
72°
63°
25
73°
62°
26
72°
63°
27
71°
62°
28
66°
60°
29
65°
60°
30
67°
61°
31
66°
62°
1
67°
63°
2
70°
62°
3
69°
62°
4
68°
61°
5
68°
61°
6
67°
58°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
May Weather in National City
National City's May 2026 forecast shows daily high temperatures ranging from 65° to 73°, with overnight lows between 55° and 63°. The average high for May is 70° with an average low of 60°. 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 National City. See also: June | July | August.