S
M
T
W
T
F
S
26
63°
46°
27
70°
48°
28
61°
48°
29
59°
48°
30
66°
52°
1
75°
50°
2
73°
52°
3
67°
48°
4
60°
45°
5
58°
43°
6
54°
40°
7
58°
44°
8
60°
47°
9
63°
48°
10
62°
46°
11
63°
49°
12
61°
49°
13
62°
49°
14
62°
47°
15
61°
48°
16
60°
47°
17
61°
44°
18
61°
43°
19
62°
46°
20
60°
43°
21
60°
42°
22
61°
43°
23
61°
45°
24
64°
49°
25
64°
49°
26
65°
48°
27
64°
47°
28
63°
44°
29
62°
43°
30
63°
46°
31
68°
48°
1
68°
48°
2
67°
50°
3
68°
48°
4
64°
49°
5
66°
49°
6
69°
52°
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 54° to 69°, with overnight lows between 40° and 52°. The average high for May is 63° with an average low of 46°. 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.
