S
M
T
W
T
F
S
26
69°
50°
27
69°
54°
28
67°
57°
29
64°
46°
30
61°
38°
1
53°
37°
2
53°
37°
3
63°
50°
4
73°
56°
5
65°
44°
6
56°
41°
7
53°
38°
8
60°
47°
9
65°
48°
10
66°
49°
11
67°
50°
12
67°
51°
13
66°
50°
14
65°
51°
15
68°
53°
16
66°
51°
17
69°
57°
18
76°
58°
19
76°
59°
20
75°
59°
21
77°
58°
22
76°
60°
23
74°
56°
24
70°
51°
25
70°
58°
26
76°
61°
27
75°
58°
28
71°
59°
29
71°
55°
30
72°
56°
31
76°
61°
1
72°
58°
2
77°
62°
3
76°
56°
4
72°
54°
5
72°
54°
6
73°
55°
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 53° to 77°, with overnight lows between 37° and 62°. The average high for May is 69° with an average low of 53°. 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.
