S
M
T
W
T
F
S
29
48°
30°
30
43°
27°
1
44°
33°
2
45°
34°
3
45°
32°
4
46°
31°
5
42°
30°
6
38°
29°
7
38°
27°
8
40°
23°
9
31°
21°
10
31°
22°
11
33°
25°
12
38°
25°
13
40°
27°
14
39°
28°
15
41°
27°
16
41°
27°
17
42°
26°
18
41°
27°
19
36°
23°
20
32°
21°
21
27°
19°
22
36°
11°
23
30°
9°
24
26°
8°
25
25°
7°
26
23°
15°
27
25°
18°
28
39°
18°
29
34°
7°
30
38°
6°
31
21°
3°
1
21°
4°
2
19°
7°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
December Weather in Walnut
Walnut's December 2026 forecast shows daily high temperatures ranging from 19° to 48°, with overnight lows between 3° and 34°. The average high for December is 35° 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 Walnut. See also: January | February | March.