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