S
M
T
W
T
F
S
29
39°
28°
30
29°
21°
1
29°
18°
2
30°
19°
3
27°
20°
4
25°
18°
5
27°
20°
6
29°
26°
7
29°
22°
8
30°
24°
9
35°
20°
10
35°
17°
11
27°
18°
12
27°
24°
13
32°
25°
14
29°
28°
15
40°
30°
16
39°
32°
17
37°
34°
18
41°
25°
19
41°
31°
20
36°
30°
21
35°
18°
22
33°
17°
23
27°
24°
24
28°
28°
25
39°
32°
26
40°
18°
27
40°
16°
28
28°
19°
29
26°
18°
30
27°
19°
31
26°
18°
1
26°
17°
2
25°
17°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
December Weather in Whittier
Whittier's December 2026 forecast shows daily high temperatures ranging from 25° to 41°, with overnight lows between 16° and 34°. The average high for December is 32° with an average low of 23°. 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 Whittier. See also: January | February | March.