S
M
T
W
T
F
S
30
87°
82°
31
87°
82°
1
88°
81°
2
88°
82°
3
88°
81°
4
87°
80°
5
87°
81°
6
88°
81°
7
87°
80°
8
86°
82°
9
88°
80°
10
88°
81°
11
90°
80°
12
90°
78°
13
89°
79°
14
88°
80°
15
89°
81°
16
90°
80°
17
90°
79°
18
89°
79°
19
89°
78°
20
90°
78°
21
89°
79°
22
88°
79°
23
88°
78°
24
87°
78°
25
89°
79°
26
90°
80°
27
90°
80°
28
89°
79°
29
89°
79°
30
88°
77°
1
88°
77°
2
87°
78°
3
86°
77°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in Key West
Key West's September 2026 forecast shows daily high temperatures ranging from 86° to 90°, with overnight lows between 77° and 82°. The average high for September is 88° with an average low of 80°. 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 West. See also: October | November | December.
