S
M
T
W
T
F
S
30
77°
59°
31
80°
59°
1
79°
52°
2
76°
51°
3
71°
54°
4
73°
57°
5
74°
60°
6
77°
53°
7
77°
50°
8
71°
52°
9
70°
58°
10
69°
58°
11
75°
56°
12
72°
53°
13
68°
54°
14
66°
50°
15
67°
48°
16
66°
47°
17
67°
52°
18
67°
48°
19
68°
53°
20
66°
55°
21
72°
52°
22
71°
45°
23
65°
50°
24
64°
53°
25
67°
46°
26
69°
44°
27
Hist. Avg.
67°
48°
28
Hist. Avg.
66°
47°
29
Hist. Avg.
66°
47°
30
Hist. Avg.
66°
47°
1
Hist. Avg.
65°
46°
2
Hist. Avg.
65°
46°
3
Hist. Avg.
64°
46°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
*Temporarily Unavailable
September Weather in Long Island
Long Island's September 2026 forecast shows daily high temperatures ranging from 64° to 80°, with overnight lows between 44° and 60°. The average high for September is 71° with an average low of 52°. 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 Long Island. See also: October | November | December.
