S
M
T
W
T
F
S
30
82°
66°
31
81°
65°
1
80°
62°
2
74°
58°
3
73°
59°
4
74°
58°
5
74°
57°
6
76°
63°
7
80°
64°
8
78°
63°
9
74°
63°
10
78°
64°
11
79°
63°
12
79°
63°
13
80°
64°
14
79°
54°
15
72°
54°
16
69°
54°
17
72°
53°
18
70°
52°
19
69°
53°
20
70°
54°
21
76°
56°
22
75°
58°
23
76°
51°
24
75°
50°
25
70°
49°
26
68°
51°
27
72°
56°
28
72°
56°
29
73°
48°
30
69°
48°
1
66°
53°
2
67°
54°
3
70°
54°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in Mattituck
Mattituck's September 2026 forecast shows daily high temperatures ranging from 66° to 82°, with overnight lows between 48° and 66°. The average high for September is 74° with an average low of 57°. 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 Mattituck. See also: October | November | December.
