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