S
M
T
W
T
F
S
26
65°
48°
27
73°
46°
28
70°
56°
29
62°
46°
30
56°
39°
1
53°
36°
2
50°
34°
3
59°
31°
4
72°
48°
5
64°
46°
6
56°
42°
7
59°
34°
8
64°
43°
9
72°
52°
10
72°
50°
11
68°
40°
12
74°
39°
13
64°
46°
14
64°
42°
15
68°
57°
16
74°
62°
17
85°
63°
18
86°
69°
19
80°
59°
20
71°
48°
21
66°
47°
22
70°
49°
23
75°
50°
24
76°
55°
25
77°
60°
26
79°
58°
27
77°
53°
28
77°
58°
29
76°
58°
30
75°
55°
31
70°
53°
1
72°
51°
2
71°
50°
3
72°
51°
4
73°
54°
5
80°
60°
6
82°
62°
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 64° to 86°, with overnight lows between 42° and 69°. The average high for May is 75° with an average low of 55°. 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.
