S
M
T
W
T
F
S
29
43°
32°
30
46°
36°
1
49°
39°
2
49°
36°
3
46°
40°
4
51°
40°
5
54°
32°
6
42°
30°
7
41°
35°
8
50°
40°
9
52°
38°
10
48°
39°
11
50°
40°
12
51°
38°
13
46°
32°
14
40°
28°
15
38°
26°
16
37°
27°
17
40°
34°
18
43°
37°
19
48°
37°
20
46°
36°
21
50°
37°
22
44°
34°
23
42°
33°
24
47°
34°
25
35°
24°
26
36°
29°
27
37°
28°
28
38°
35°
29
49°
31°
30
50°
30°
31
40°
30°
1
41°
27°
2
44°
24°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
December Weather in Riverhead
Riverhead's December 2026 forecast shows daily high temperatures ranging from 35° to 54°, with overnight lows between 24° and 40°. The average high for December is 45° with an average low of 33°. 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 Riverhead. See also: January | February | March.
