S
M
T
W
T
F
S
30
80°
52°
31
76°
66°
1
77°
66°
2
72°
68°
3
79°
68°
4
81°
64°
5
78°
60°
6
73°
60°
7
78°
65°
8
80°
64°
9
75°
68°
10
80°
64°
11
75°
64°
12
77°
62°
13
77°
63°
14
73°
62°
15
74°
61°
16
72°
64°
17
75°
62°
18
69°
56°
19
74°
63°
20
75°
62°
21
72°
59°
22
70°
61°
23
71°
62°
24
75°
60°
25
70°
60°
26
73°
62°
27
74°
62°
28
74°
58°
29
67°
55°
30
67°
57°
1
66°
55°
2
65°
56°
3
66°
58°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in Shelter Island
Shelter Island's September 2026 forecast shows daily high temperatures ranging from 65° to 81°, with overnight lows between 55° and 68°. The average high for September is 73° 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 Shelter Island. See also: October | November | December.
