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