S
M
T
W
T
F
S
30
90°
77°
31
90°
82°
1
90°
80°
2
90°
83°
3
91°
83°
4
91°
80°
5
90°
78°
6
91°
82°
7
89°
82°
8
91°
80°
9
90°
82°
10
89°
81°
11
90°
84°
12
94°
78°
13
89°
78°
14
90°
79°
15
91°
82°
16
90°
81°
17
88°
80°
18
87°
82°
19
88°
81°
20
87°
82°
21
89°
81°
22
88°
83°
23
89°
80°
24
88°
80°
25
87°
81°
26
89°
80°
27
87°
81°
28
89°
78°
29
85°
81°
30
85°
81°
1
86°
80°
2
85°
80°
3
86°
81°
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 85° to 91°, with overnight lows between 78° and 83°. The average high for September is 88° with an average low of 81°. 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.
