S
M
T
W
T
F
S
29
38°
22°
30
41°
29°
1
45°
32°
2
42°
31°
3
45°
30°
4
47°
33°
5
46°
24°
6
36°
22°
7
36°
28°
8
41°
33°
9
42°
32°
10
41°
33°
11
45°
32°
12
46°
30°
13
38°
25°
14
36°
23°
15
32°
21°
16
32°
21°
17
35°
26°
18
42°
30°
19
45°
30°
20
43°
31°
21
44°
28°
22
34°
26°
23
37°
28°
24
44°
30°
25
32°
15°
26
32°
15°
27
33°
19°
28
32°
27°
29
44°
25°
30
43°
20°
31
33°
15°
1
32°
16°
2
31°
13°
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 31° to 47°, with overnight lows between 13° and 33°. The average high for December is 39° 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.
