S
M
T
W
T
F
S
29
41°
31°
30
46°
32°
1
45°
34°
2
47°
32°
3
44°
30°
4
42°
33°
5
47°
35°
6
47°
32°
7
48°
27°
8
47°
27°
9
37°
26°
10
41°
28°
11
41°
30°
12
38°
30°
13
38°
31°
14
39°
31°
15
45°
25°
16
44°
23°
17
34°
24°
18
36°
22°
19
33°
25°
20
37°
28°
21
38°
29°
22
41°
28°
23
42°
24°
24
37°
20°
25
32°
20°
26
31°
28°
27
37°
25°
28
40°
23°
29
35°
19°
30
33°
23°
31
34°
10°
1
34°
8°
2
23°
11°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
December Weather in Mount Prospect
Mount Prospect's December 2026 forecast shows daily high temperatures ranging from 23° to 48°, with overnight lows between 8° and 35°. The average high for December is 39° with an average low of 26°. 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 Prospect. See also: January | February | March.
