S
M
T
W
T
F
S
29
45°
34°
30
46°
33°
1
45°
32°
2
45°
32°
3
40°
31°
4
42°
31°
5
44°
30°
6
44°
28°
7
37°
26°
8
34°
25°
9
31°
26°
10
36°
27°
11
37°
30°
12
39°
29°
13
39°
29°
14
32°
20°
15
32°
23°
16
35°
26°
17
39°
27°
18
38°
26°
19
37°
19°
20
34°
18°
21
30°
17°
22
31°
20°
23
30°
25°
24
33°
24°
25
33°
21°
26
32°
13°
27
30°
10°
28
26°
9°
29
26°
11°
30
27°
24°
31
30°
17°
1
34°
15°
2
28°
10°
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 26° to 46°, with overnight lows between 9° and 34°. The average high for December is 35° with an average low of 23°. 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.
