S
M
T
W
T
F
S
29
82°
71°
30
81°
65°
1
81°
62°
2
75°
64°
3
75°
66°
4
78°
68°
5
78°
69°
6
79°
69°
7
79°
68°
8
80°
69°
9
80°
69°
10
81°
68°
11
81°
69°
12
80°
69°
13
81°
68°
14
80°
68°
15
80°
67°
16
79°
68°
17
80°
67°
18
76°
68°
19
77°
67°
20
78°
66°
21
79°
67°
22
80°
68°
23
79°
69°
24
80°
68°
25
80°
62°
26
79°
63°
27
73°
68°
28
77°
68°
29
79°
67°
30
80°
68°
31
80°
64°
1
79°
59°
2
79°
61°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
December Weather in Key Largo
Key Largo's December 2026 forecast shows daily high temperatures ranging from 73° to 82°, with overnight lows between 59° and 71°. The average high for December is 79° with an average low of 67°. 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 Largo. See also: January | February | March.