S
M
T
W
T
F
S
29
46°
39°
30
47°
39°
1
48°
38°
2
46°
35°
3
42°
33°
4
42°
32°
5
43°
32°
6
42°
33°
7
46°
38°
8
46°
37°
9
45°
38°
10
47°
38°
11
47°
39°
12
46°
37°
13
46°
36°
14
42°
32°
15
43°
32°
16
43°
33°
17
42°
32°
18
42°
32°
19
43°
33°
20
42°
37°
21
45°
37°
22
46°
36°
23
48°
38°
24
47°
38°
25
48°
37°
26
48°
38°
27
46°
37°
28
47°
38°
29
46°
37°
30
47°
39°
31
48°
37°
1
48°
35°
2
47°
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 42° to 48°, with overnight lows between 32° and 39°. The average high for December is 45° with an average low of 36°. 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.
