S
M
T
W
T
F
S
29
50°
33°
30
47°
31°
1
41°
32°
2
49°
31°
3
43°
30°
4
41°
29°
5
46°
30°
6
39°
30°
7
42°
29°
8
43°
30°
9
38°
28°
10
36°
29°
11
36°
28°
12
39°
26°
13
34°
23°
14
36°
27°
15
41°
27°
16
40°
29°
17
43°
27°
18
41°
26°
19
40°
26°
20
32°
25°
21
30°
25°
22
39°
26°
23
34°
25°
24
29°
24°
25
27°
17°
26
30°
21°
27
34°
19°
28
32°
16°
29
32°
16°
30
33°
6°
31
27°
4°
1
21°
8°
2
22°
6°
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 21° to 50°, with overnight lows between 4° and 33°. The average high for December is 37° with an average low of 24°. 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.
