S
M
T
W
T
F
S
30
90°
67°
31
94°
70°
1
98°
73°
2
98°
74°
3
98°
74°
4
98°
73°
5
96°
71°
6
84°
64°
7
83°
60°
8
90°
60°
9
91°
71°
10
76°
68°
11
84°
64°
12
91°
70°
13
83°
59°
14
82°
56°
15
97°
68°
16
92°
73°
17
94°
72°
18
90°
70°
19
90°
70°
20
88°
70°
21
70°
60°
22
71°
57°
23
65°
59°
24
71°
58°
25
N/A
26
77°
55°
27
76°
50°
28
N/A
29
82°
49°
30
88°
64°
1
89°
60°
2
66°
46°
3
70°
46°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
*Temporarily Unavailable
September Weather in Charleston
Charleston's September 2026 forecast shows daily high temperatures ranging from 66° to 89°, with overnight lows between 46° and 60°. The average high for September is 75° with an average low of 51°. 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 Charleston. See also: October | November | December.
