S
M
T
W
T
F
S
29
82°
73°
30
85°
71°
1
85°
72°
2
84°
71°
3
83°
70°
4
85°
66°
5
84°
63°
6
81°
63°
7
76°
64°
8
76°
64°
9
79°
65°
10
80°
63°
11
76°
62°
12
75°
64°
13
76°
64°
14
77°
63°
15
77°
63°
16
75°
64°
17
76°
64°
18
76°
63°
19
77°
64°
20
77°
66°
21
78°
68°
22
79°
68°
23
82°
69°
24
82°
67°
25
81°
66°
26
81°
67°
27
80°
67°
28
81°
66°
29
81°
67°
30
80°
67°
31
82°
66°
1
81°
66°
2
80°
65°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
December Weather in Key Biscayne
Key Biscayne's December 2026 forecast shows daily high temperatures ranging from 75° to 85°, with overnight lows between 62° and 73°. The average high for December is 80° with an average low of 66°. 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 Key Biscayne. See also: January | February | March.
