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