S
M
T
W
T
F
S
26
65°
44°
27
57°
40°
28
53°
39°
29
54°
42°
30
55°
44°
1
56°
40°
2
57°
37°
3
57°
40°
4
63°
48°
5
67°
49°
6
67°
42°
7
58°
41°
8
63°
46°
9
64°
46°
10
66°
49°
11
68°
51°
12
70°
51°
13
69°
49°
14
70°
47°
15
65°
43°
16
65°
42°
17
67°
45°
18
66°
46°
19
66°
43°
20
68°
47°
21
70°
53°
22
71°
53°
23
70°
47°
24
71°
44°
25
65°
46°
26
67°
46°
27
67°
45°
28
68°
46°
29
68°
46°
30
70°
49°
31
72°
53°
1
77°
56°
2
76°
52°
3
70°
51°
4
69°
53°
5
78°
52°
6
76°
58°
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 53° to 78°, with overnight lows between 37° and 58°. The average high for May is 66° with an average low of 47°. 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.
