S
M
T
W
T
F
S
30
90°
76°
31
89°
75°
1
88°
76°
2
88°
75°
3
85°
72°
4
84°
70°
5
85°
70°
6
85°
69°
7
87°
71°
8
88°
73°
9
88°
74°
10
87°
74°
11
88°
73°
12
88°
74°
13
86°
74°
14
86°
71°
15
87°
72°
16
88°
69°
17
87°
71°
18
82°
65°
19
86°
66°
20
80°
68°
21
81°
70°
22
82°
68°
23
82°
69°
24
85°
65°
25
85°
68°
26
79°
67°
27
80°
65°
28
82°
68°
29
80°
69°
30
83°
65°
1
82°
68°
2
81°
68°
3
81°
67°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in Seabrook Island
Seabrook Island's September 2026 forecast shows daily high temperatures ranging from 79° to 90°, with overnight lows between 65° and 76°. The average high for September is 85° with an average low of 70°. 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 Seabrook Island. See also: October | November | December.