S
M
T
W
T
F
S
26
73°
48°
27
73°
48°
28
61°
43°
29
59°
38°
30
57°
35°
1
57°
35°
2
62°
28°
3
75°
46°
4
80°
46°
5
60°
37°
6
54°
31°
7
66°
31°
8
75°
34°
9
70°
42°
10
72°
35°
11
68°
32°
12
81°
55°
13
74°
46°
14
79°
39°
15
88°
59°
16
82°
59°
17
81°
62°
18
76°
62°
19
65°
45°
20
62°
41°
21
59°
50°
22
65°
49°
23
75°
53°
24
84°
46°
25
87°
61°
26
88°
61°
27
90°
62°
28
85°
56°
29
85°
58°
30
84°
56°
31
78°
55°
1
83°
56°
2
82°
54°
3
80°
59°
4
82°
60°
5
88°
63°
6
90°
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 78° to 90°, with overnight lows between 54° and 63°. The average high for May is 85° with an average low of 59°. 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.
