S
M
T
W
T
F
S
29
44°
31°
30
44°
30°
1
42°
29°
2
41°
29°
3
41°
28°
4
43°
28°
5
42°
27°
6
36°
24°
7
32°
18°
8
28°
17°
9
31°
20°
10
38°
25°
11
38°
25°
12
40°
24°
13
36°
25°
14
29°
23°
15
34°
21°
16
37°
22°
17
36°
23°
18
34°
20°
19
33°
18°
20
31°
9°
21
30°
15°
22
26°
16°
23
35°
20°
24
32°
18°
25
35°
9°
26
31°
13°
27
25°
13°
28
29°
8°
29
28°
13°
30
26°
16°
31
28°
8°
1
33°
4°
2
22°
5°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
December Weather in Monticello
Monticello's December 2026 forecast shows daily high temperatures ranging from 22° to 44°, with overnight lows between 4° and 31°. The average high for December is 34° with an average low of 19°. 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 Monticello. See also: January | February | March.
