S
M
T
W
T
F
S
29
49°
36°
30
46°
40°
1
47°
39°
2
48°
40°
3
50°
37°
4
38°
35°
5
44°
35°
6
55°
32°
7
44°
30°
8
43°
26°
9
40°
25°
10
37°
23°
11
36°
24°
12
37°
25°
13
37°
29°
14
38°
33°
15
44°
34°
16
46°
32°
17
50°
27°
18
50°
27°
19
37°
24°
20
37°
22°
21
38°
24°
22
34°
22°
23
36°
26°
24
36°
31°
25
42°
36°
26
47°
37°
27
49°
34°
28
50°
32°
29
44°
30°
30
43°
31°
31
42°
29°
1
44°
26°
2
39°
28°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
December Weather in West Islip
West Islip's December 2026 forecast shows daily high temperatures ranging from 34° to 55°, with overnight lows between 22° and 40°. The average high for December is 43° with an average low of 30°. 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 West Islip. See also: January | February | March.
