S
M
T
W
T
F
S
30
83°
65°
31
84°
68°
1
82°
65°
2
81°
67°
3
81°
68°
4
80°
66°
5
81°
66°
6
79°
65°
7
79°
65°
8
78°
64°
9
79°
65°
10
78°
65°
11
80°
64°
12
80°
65°
13
79°
66°
14
79°
64°
15
77°
65°
16
78°
63°
17
77°
64°
18
75°
61°
19
74°
54°
20
70°
58°
21
70°
62°
22
71°
53°
23
70°
53°
24
68°
55°
25
70°
60°
26
74°
57°
27
68°
54°
28
68°
53°
29
66°
52°
30
67°
52°
1
67°
58°
2
69°
58°
3
68°
50°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in South Setauket
South Setauket's September 2026 forecast shows daily high temperatures ranging from 66° to 84°, with overnight lows between 50° and 68°. The average high for September is 75° with an average low of 61°. 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 South Setauket. See also: October | November | December.
