S
M
T
W
T
F
S
26
66°
52°
27
72°
47°
28
78°
46°
29
78°
50°
30
86°
52°
1
86°
54°
2
73°
55°
3
73°
54°
4
66°
51°
5
69°
50°
6
80°
52°
7
84°
52°
8
86°
54°
9
91°
58°
10
96°
61°
11
99°
64°
12
98°
61°
13
95°
60°
14
91°
59°
15
90°
57°
16
89°
58°
17
82°
52°
18
86°
56°
19
85°
57°
20
87°
57°
21
87°
56°
22
86°
57°
23
87°
58°
24
88°
58°
25
88°
57°
26
87°
58°
27
87°
57°
28
84°
56°
29
83°
57°
30
83°
57°
31
84°
58°
1
86°
59°
2
89°
58°
3
88°
59°
4
86°
58°
5
87°
58°
6
82°
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 66° to 99°, with overnight lows between 50° and 64°. The average high for May is 86° with an average low of 57°. 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.
