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