S
M
T
W
T
F
S
29
42°
25°
30
46°
27°
1
48°
25°
2
47°
23°
3
45°
21°
4
44°
23°
5
46°
22°
6
50°
25°
7
44°
19°
8
47°
18°
9
42°
18°
10
44°
13°
11
45°
20°
12
47°
14°
13
39°
13°
14
Hist. Avg.
36°
16°
15
Hist. Avg.
36°
16°
16
Hist. Avg.
36°
16°
17
Hist. Avg.
36°
16°
18
Hist. Avg.
36°
16°
19
Hist. Avg.
36°
16°
20
Hist. Avg.
36°
16°
21
Hist. Avg.
36°
16°
22
Hist. Avg.
36°
16°
23
Hist. Avg.
36°
16°
24
Hist. Avg.
36°
16°
25
Hist. Avg.
36°
16°
26
Hist. Avg.
36°
16°
27
Hist. Avg.
36°
16°
28
Hist. Avg.
36°
16°
29
Hist. Avg.
36°
16°
30
Hist. Avg.
36°
16°
31
Hist. Avg.
36°
16°
1
Hist. Avg.
36°
16°
2
Hist. Avg.
37°
16°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
*Temporarily Unavailable
December Weather in Keystone
Keystone's December 2026 forecast shows daily high temperatures ranging from 39° to 50°, with overnight lows between 13° and 27°. The average high for December is 45° with an average low of 20°. 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.
