S
M
T
W
T
F
S
26
51°
41°
27
67°
37°
28
65°
42°
29
65°
48°
30
71°
48°
1
65°
40°
2
58°
47°
3
61°
42°
4
77°
50°
5
84°
62°
6
70°
62°
7
63°
46°
8
70°
42°
9
75°
55°
10
83°
54°
11
62°
46°
12
69°
40°
13
75°
56°
14
63°
49°
15
70°
48°
16
83°
62°
17
88°
65°
18
92°
69°
19
94°
70°
20
93°
66°
21
73°
53°
22
68°
55°
23
77°
56°
24
77°
58°
25
81°
61°
26
82°
64°
27
85°
58°
28
83°
62°
29
76°
63°
30
82°
63°
31
81°
62°
1
76°
60°
2
77°
59°
3
76°
57°
4
76°
57°
5
79°
64°
6
85°
66°
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 94°, with overnight lows between 48° and 70°. The average high for May is 80° with an average low of 60°. 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.
