S
M
T
W
T
F
S
30
91°
80°
31
90°
81°
1
90°
82°
2
89°
83°
3
88°
83°
4
89°
83°
5
90°
80°
6
89°
81°
7
89°
78°
8
88°
80°
9
89°
78°
10
90°
77°
11
89°
79°
12
86°
80°
13
86°
80°
14
88°
80°
15
86°
80°
16
86°
79°
17
88°
80°
18
88°
80°
19
89°
79°
20
88°
79°
21
87°
78°
22
87°
79°
23
84°
77°
24
86°
76°
25
86°
79°
26
88°
78°
27
85°
79°
28
86°
79°
29
87°
78°
30
86°
79°
1
85°
79°
2
86°
78°
3
85°
77°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in Key Largo
Key Largo's September 2026 forecast shows daily high temperatures ranging from 84° to 90°, with overnight lows between 76° and 83°. The average high for September is 87° with an average low of 79°. AccuWeather's monthly forecast extends further ahead than any other source, with day-by-day RealFeel® Temperatures giving a complete picture of how September weather will actually feel in Key Largo. See also: October | November | December.
