S
M
T
W
T
F
S
29
55°
39°
30
55°
40°
1
54°
32°
2
41°
29°
3
43°
31°
4
50°
34°
5
51°
37°
6
41°
29°
7
39°
23°
8
37°
22°
9
37°
25°
10
40°
28°
11
44°
27°
12
46°
29°
13
43°
27°
14
39°
22°
15
39°
26°
16
40°
30°
17
41°
27°
18
41°
21°
19
38°
20°
20
36°
19°
21
34°
20°
22
35°
26°
23
41°
25°
24
38°
23°
25
36°
18°
26
36°
18°
27
35°
19°
28
35°
19°
29
36°
23°
30
35°
20°
31
35°
17°
1
36°
13°
2
34°
13°
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 34° to 55°, with overnight lows between 13° and 40°. The average high for December is 40° with an average low of 25°. 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.
