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