S
M
T
W
T
F
S
29
49°
28°
30
37°
22°
1
34°
21°
2
35°
29°
3
42°
30°
4
39°
29°
5
35°
28°
6
35°
21°
7
31°
18°
8
33°
28°
9
44°
28°
10
45°
27°
11
44°
28°
12
45°
27°
13
45°
27°
14
37°
24°
15
35°
26°
16
38°
18°
17
37°
14°
18
32°
10°
19
33°
11°
20
27°
14°
21
32°
20°
22
35°
13°
23
34°
15°
24
31°
18°
25
35°
21°
26
35°
23°
27
38°
17°
28
35°
11°
29
32°
13°
30
33°
10°
31
29°
8°
1
27°
21°
2
31°
23°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
December Weather in Keystone
Keystone's December 2026 forecast shows daily high temperatures ranging from 27° to 49°, with overnight lows between 8° and 30°. The average high for December is 36° with an average low of 21°. 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 Keystone. See also: January | February | March.
