S
M
T
W
T
F
S
29
43°
33°
30
44°
32°
1
38°
31°
2
39°
32°
3
43°
33°
4
42°
32°
5
44°
30°
6
36°
28°
7
33°
29°
8
36°
19°
9
27°
21°
10
31°
22°
11
31°
23°
12
32°
27°
13
35°
26°
14
37°
26°
15
36°
27°
16
36°
27°
17
37°
26°
18
35°
26°
19
36°
25°
20
32°
25°
21
26°
21°
22
27°
21°
23
30°
15°
24
28°
9°
25
24°
7°
26
21°
12°
27
22°
15°
28
30°
10°
29
30°
13°
30
34°
8°
31
33°
8°
1
18°
5°
2
18°
4°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
December Weather in Waterloo
Waterloo's December 2026 forecast shows daily high temperatures ranging from 18° to 44°, with overnight lows between 4° and 33°. The average high for December is 33° with an average low of 21°. AccuWeather's monthly forecast extends further ahead than any other source, with day-by-day RealFeel® Temperatures giving a complete picture of how December weather will actually feel in Waterloo. See also: January | February | March.
