S
M
T
W
T
F
S
29
36°
27°
30
38°
24°
1
34°
24°
2
36°
19°
3
34°
20°
4
31°
26°
5
37°
31°
6
40°
35°
7
46°
27°
8
47°
25°
9
43°
22°
10
32°
24°
11
34°
21°
12
35°
22°
13
33°
24°
14
32°
22°
15
29°
18°
16
30°
23°
17
30°
26°
18
33°
27°
19
32°
30°
20
41°
27°
21
44°
21°
22
41°
24°
23
33°
28°
24
40°
26°
25
41°
25°
26
38°
25°
27
34°
14°
28
33°
15°
29
25°
9°
30
27°
8°
31
26°
10°
1
20°
12°
2
23°
20°
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 20° to 47°, with overnight lows between 8° and 35°. The average high for December is 35° with an average low of 22°. 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.
