S
M
T
W
T
F
S
29
46°
31°
30
54°
29°
1
54°
27°
2
49°
32°
3
54°
25°
4
53°
24°
5
40°
23°
6
39°
22°
7
39°
23°
8
40°
28°
9
43°
33°
10
51°
29°
11
51°
29°
12
42°
26°
13
40°
27°
14
39°
24°
15
40°
20°
16
38°
18°
17
36°
20°
18
35°
30°
19
42°
30°
20
43°
25°
21
48°
26°
22
40°
34°
23
49°
35°
24
49°
30°
25
48°
29°
26
47°
29°
27
43°
30°
28
46°
31°
29
47°
32°
30
47°
33°
31
50°
30°
1
50°
29°
2
48°
28°
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 35° to 54°, with overnight lows between 18° and 35°. The average high for December is 45° with an average low of 28°. 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.
