S
M
T
W
T
F
S
26
77°
48°
27
75°
55°
28
63°
50°
29
57°
41°
30
61°
36°
1
59°
36°
2
59°
41°
3
72°
45°
4
79°
50°
5
55°
45°
6
57°
39°
7
66°
39°
8
63°
48°
9
79°
52°
10
66°
43°
11
72°
45°
12
81°
52°
13
72°
50°
14
77°
55°
15
84°
64°
16
81°
63°
17
87°
69°
18
80°
60°
19
78°
51°
20
63°
48°
21
66°
51°
22
72°
52°
23
76°
56°
24
79°
57°
25
79°
58°
26
80°
60°
27
79°
56°
28
78°
59°
29
80°
57°
30
72°
56°
31
73°
56°
1
72°
53°
2
73°
55°
3
74°
61°
4
81°
63°
5
83°
64°
6
82°
64°
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 63° to 87°, with overnight lows between 48° and 69°. The average high for May is 77° with an average low of 58°. 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.
