S
M
T
W
T
F
S
29
54°
39°
30
54°
31°
1
49°
27°
2
40°
26°
3
47°
37°
4
52°
37°
5
47°
36°
6
40°
32°
7
39°
25°
8
37°
26°
9
41°
30°
10
45°
33°
11
48°
32°
12
52°
32°
13
48°
34°
14
44°
28°
15
45°
27°
16
44°
27°
17
40°
22°
18
37°
20°
19
38°
18°
20
35°
16°
21
33°
28°
22
38°
19°
23
39°
23°
24
37°
17°
25
35°
23°
26
35°
29°
27
39°
26°
28
38°
19°
29
36°
21°
30
34°
22°
31
34°
16°
1
35°
12°
2
32°
18°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
December Weather in Riverside
Riverside's December 2026 forecast shows daily high temperatures ranging from 32° to 54°, with overnight lows between 12° and 39°. The average high for December is 41° with an average low of 26°. 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 Riverside. See also: January | February | March.
