S
M
T
W
T
F
S
30
88°
78°
31
88°
80°
1
90°
78°
2
87°
78°
3
89°
79°
4
89°
78°
5
90°
79°
6
88°
78°
7
89°
79°
8
88°
78°
9
88°
78°
10
87°
79°
11
88°
79°
12
88°
78°
13
89°
78°
14
89°
79°
15
88°
77°
16
89°
77°
17
88°
76°
18
87°
77°
19
87°
77°
20
88°
78°
21
86°
78°
22
88°
77°
23
87°
77°
24
88°
78°
25
87°
77°
26
86°
76°
27
86°
77°
28
87°
76°
29
88°
77°
30
89°
77°
1
Hist. Avg.
88°
78°
2
Hist. Avg.
88°
78°
3
Hist. Avg.
88°
78°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in Long Key
Long Key's September 2026 forecast shows daily high temperatures ranging from 86° to 90°, with overnight lows between 76° and 80°. The average high for September is 88° with an average low of 78°. 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 Long Key. See also: October | November | December.
