S
M
T
W
T
F
S
26
68°
39°
27
67°
48°
28
65°
46°
29
57°
37°
30
56°
36°
1
51°
36°
2
57°
42°
3
64°
44°
4
65°
47°
5
59°
42°
6
58°
42°
7
58°
42°
8
59°
43°
9
64°
45°
10
71°
53°
11
61°
48°
12
62°
45°
13
62°
42°
14
63°
43°
15
63°
44°
16
67°
48°
17
68°
52°
18
73°
54°
19
72°
50°
20
68°
47°
21
66°
47°
22
66°
46°
23
73°
55°
24
76°
56°
25
76°
55°
26
72°
50°
27
68°
52°
28
73°
56°
29
77°
57°
30
79°
58°
31
79°
58°
1
80°
59°
2
81°
60°
3
81°
60°
4
78°
54°
5
71°
53°
6
73°
60°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
May Weather in Janesville
Janesville's May 2026 forecast shows daily high temperatures ranging from 51° to 81°, with overnight lows between 36° and 60°. The average high for May is 68° with an average low of 49°. 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 Janesville. See also: June | July | August.
