S
M
T
W
T
F
S
30
90°
77°
31
89°
79°
1
90°
79°
2
89°
79°
3
86°
79°
4
91°
77°
5
90°
76°
6
93°
74°
7
88°
75°
8
89°
78°
9
91°
79°
10
90°
76°
11
92°
76°
12
90°
75°
13
91°
76°
14
94°
78°
15
85°
75°
16
88°
74°
17
90°
73°
18
88°
71°
19
89°
72°
20
88°
74°
21
87°
73°
22
88°
72°
23
85°
74°
24
86°
71°
25
88°
72°
26
88°
72°
27
85°
71°
28
86°
70°
29
83°
74°
30
83°
73°
1
84°
72°
2
82°
70°
3
84°
72°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in Downtown Jacksonville
Downtown Jacksonville's September 2026 forecast shows daily high temperatures ranging from 82° to 90°, with overnight lows between 70° and 75°. The average high for September is 86° with an average low of 72°. 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 Downtown Jacksonville. See also: October | November | December.
