S
M
T
W
T
F
S
26
55°
32°
27
67°
39°
28
51°
48°
29
54°
43°
30
52°
29°
1
53°
33°
2
45°
28°
3
56°
35°
4
72°
52°
5
73°
54°
6
57°
32°
7
58°
31°
8
57°
39°
9
61°
49°
10
62°
32°
11
60°
30°
12
67°
37°
13
65°
42°
14
46°
42°
15
66°
41°
16
75°
54°
17
83°
58°
18
89°
56°
19
82°
61°
20
74°
49°
21
65°
45°
22
60°
45°
23
51°
48°
24
60°
53°
25
69°
51°
26
75°
51°
27
75°
52°
28
73°
53°
29
74°
54°
30
74°
53°
31
75°
52°
1
76°
53°
2
75°
49°
3
77°
53°
4
76°
55°
5
77°
55°
6
76°
54°
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 77°, with overnight lows between 45° and 55°. The average high for May is 71° 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 Janesville. See also: June | July | August.
