S
M
T
W
T
F
S
29
46°
29°
30
46°
30°
1
42°
27°
2
46°
24°
3
40°
28°
4
41°
33°
5
48°
39°
6
53°
36°
7
55°
32°
8
55°
30°
9
42°
31°
10
47°
34°
11
46°
33°
12
48°
27°
13
45°
24°
14
37°
19°
15
36°
26°
16
36°
29°
17
38°
32°
18
39°
34°
19
44°
38°
20
52°
32°
21
54°
25°
22
45°
29°
23
42°
31°
24
44°
30°
25
42°
30°
26
43°
19°
27
39°
17°
28
39°
20°
29
34°
12°
30
34°
12°
31
32°
11°
1
29°
18°
2
33°
20°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
December Weather in Bethalto
Bethalto's December 2026 forecast shows daily high temperatures ranging from 29° to 55°, with overnight lows between 11° and 39°. The average high for December is 43° with an average low of 27°. 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 Bethalto. See also: January | February | March.
