S
M
T
W
T
F
S
29
50°
39°
30
56°
39°
1
55°
40°
2
55°
35°
3
43°
33°
4
50°
31°
5
54°
38°
6
53°
35°
7
41°
30°
8
40°
24°
9
40°
23°
10
41°
24°
11
38°
27°
12
39°
25°
13
40°
24°
14
40°
23°
15
39°
29°
16
41°
31°
17
42°
33°
18
47°
29°
19
46°
23°
20
40°
22°
21
38°
21°
22
37°
22°
23
40°
27°
24
39°
23°
25
38°
21°
26
37°
19°
27
36°
21°
28
35°
19°
29
37°
22°
30
38°
26°
31
44°
21°
1
43°
18°
2
36°
15°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
December Weather in Mount Vernon
Mount Vernon's December 2026 forecast shows daily high temperatures ranging from 35° to 56°, with overnight lows between 15° and 40°. 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 Mount Vernon. See also: January | February | March.
