S
M
T
W
T
F
S
26
65°
48°
27
73°
46°
28
70°
56°
29
62°
46°
30
56°
39°
1
53°
36°
2
50°
34°
3
59°
31°
4
72°
48°
5
64°
46°
6
56°
42°
7
59°
34°
8
64°
43°
9
72°
52°
10
72°
50°
11
68°
40°
12
74°
39°
13
64°
46°
14
64°
40°
15
64°
38°
16
74°
60°
17
86°
66°
18
85°
69°
19
82°
63°
20
66°
48°
21
64°
47°
22
68°
49°
23
75°
57°
24
74°
59°
25
74°
57°
26
79°
56°
27
77°
55°
28
79°
56°
29
78°
54°
30
79°
59°
31
78°
58°
1
79°
60°
2
79°
59°
3
75°
55°
4
72°
52°
5
73°
53°
6
75°
60°
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 64° to 86°, with overnight lows between 47° and 69°. The average high for May is 76° 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.
