S
M
T
W
T
F
S
29
46°
39°
30
46°
36°
1
47°
39°
2
48°
37°
3
45°
32°
4
41°
32°
5
41°
33°
6
42°
33°
7
42°
34°
8
41°
32°
9
41°
32°
10
42°
31°
11
45°
36°
12
46°
36°
13
46°
35°
14
45°
36°
15
46°
36°
16
45°
35°
17
44°
35°
18
45°
36°
19
45°
36°
20
44°
35°
21
46°
35°
22
46°
36°
23
44°
34°
24
45°
35°
25
44°
36°
26
43°
35°
27
45°
37°
28
46°
36°
29
47°
37°
30
47°
37°
31
46°
36°
1
47°
34°
2
45°
33°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
December Weather in Dumbarton
Dumbarton's December 2026 forecast shows daily high temperatures ranging from 41° to 48°, with overnight lows between 31° and 39°. The average high for December is 45° with an average low of 35°. 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 Dumbarton. See also: January | February | March.
