S
M
T
W
T
F
S
26
81°
51°
27
83°
61°
28
66°
55°
29
64°
50°
30
67°
40°
1
64°
43°
2
58°
40°
3
75°
56°
4
76°
58°
5
65°
47°
6
55°
42°
7
59°
44°
8
67°
51°
9
69°
52°
10
71°
52°
11
72°
53°
12
73°
52°
13
72°
51°
14
75°
54°
15
73°
59°
16
72°
58°
17
76°
60°
18
76°
60°
19
77°
59°
20
78°
61°
21
79°
61°
22
77°
60°
23
75°
55°
24
73°
58°
25
78°
62°
26
77°
59°
27
75°
56°
28
74°
57°
29
74°
54°
30
75°
62°
31
82°
63°
1
77°
63°
2
83°
64°
3
83°
63°
4
76°
57°
5
76°
56°
6
75°
57°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
May Weather in Waterloo
Waterloo's May 2026 forecast shows daily high temperatures ranging from 55° to 83°, with overnight lows between 40° and 64°. The average high for May is 73° with an average low of 56°. 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 Waterloo. See also: June | July | August.
