S
M
T
W
T
F
S
26
59°
44°
27
58°
44°
28
56°
43°
29
60°
45°
30
57°
44°
1
58°
47°
2
59°
45°
3
58°
41°
4
58°
41°
5
57°
42°
6
59°
41°
7
61°
44°
8
61°
49°
9
64°
49°
10
65°
45°
11
61°
42°
12
61°
43°
13
60°
43°
14
61°
46°
15
62°
44°
16
63°
45°
17
63°
46°
18
64°
50°
19
65°
47°
20
64°
48°
21
66°
50°
22
68°
51°
23
67°
54°
24
67°
55°
25
73°
54°
26
72°
54°
27
67°
55°
28
75°
57°
29
77°
51°
30
71°
51°
31
69°
53°
1
68°
52°
2
70°
51°
3
72°
57°
4
78°
58°
5
78°
58°
6
77°
53°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
May Weather in Johnston
Johnston's May 2026 forecast shows daily high temperatures ranging from 56° to 78°, with overnight lows between 41° and 58°. The average high for May is 65° with an average low of 48°. 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 Johnston. See also: June | July | August.
