S
M
T
W
T
F
S
30
80°
52°
31
76°
66°
1
77°
66°
2
72°
66°
3
79°
66°
4
82°
62°
5
77°
58°
6
73°
56°
7
77°
60°
8
76°
62°
9
74°
64°
10
79°
59°
11
73°
58°
12
75°
57°
13
78°
61°
14
71°
58°
15
72°
66°
16
70°
60°
17
73°
58°
18
68°
52°
19
72°
59°
20
73°
58°
21
70°
55°
22
68°
57°
23
69°
58°
24
73°
56°
25
69°
56°
26
71°
58°
27
72°
58°
28
72°
54°
29
64°
51°
30
65°
53°
1
64°
51°
2
63°
52°
3
62°
54°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in Sag Harbor
Sag Harbor's September 2026 forecast shows daily high temperatures ranging from 62° to 82°, with overnight lows between 51° and 66°. The average high for September is 72° with an average low of 58°. 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 Sag Harbor. See also: October | November | December.
