S
M
T
W
T
F
S
26
63°
47°
27
66°
47°
28
71°
42°
29
72°
43°
30
69°
42°
1
66°
49°
2
64°
52°
3
66°
52°
4
64°
46°
5
65°
53°
6
74°
53°
7
72°
51°
8
71°
52°
9
74°
48°
10
70°
52°
11
79°
54°
12
69°
51°
13
75°
48°
14
74°
45°
15
80°
45°
16
78°
48°
17
76°
45°
18
84°
52°
19
89°
44°
20
83°
50°
21
81°
48°
22
71°
51°
23
67°
50°
24
69°
51°
25
67°
49°
26
74°
49°
27
78°
51°
28
76°
53°
29
76°
52°
30
81°
49°
31
76°
51°
1
75°
53°
2
77°
52°
3
76°
53°
4
77°
57°
5
72°
51°
6
74°
51°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
May Weather in Napa County Airport
Napa County Airport's May 2026 forecast shows daily high temperatures ranging from 67° to 81°, with overnight lows between 49° and 57°. The average high for May is 74° with an average low of 51°. 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 Napa County Airport. See also: June | July | August.
