S
M
T
W
T
F
S
30
90°
59°
31
82°
59°
1
82°
64°
2
88°
60°
3
88°
64°
4
86°
66°
5
90°
63°
6
89°
57°
7
80°
56°
8
80°
56°
9
81°
62°
10
86°
62°
11
86°
58°
12
80°
56°
13
78°
55°
14
79°
61°
15
84°
56°
16
86°
53°
17
78°
53°
18
76°
52°
19
76°
53°
20
77°
53°
21
74°
52°
22
74°
53°
23
76°
52°
24
76°
57°
25
80°
57°
26
81°
58°
27
82°
53°
28
78°
58°
29
78°
57°
30
79°
53°
1
73°
54°
2
74°
51°
3
72°
48°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in New Haven
New Haven's September 2026 forecast shows daily high temperatures ranging from 72° to 90°, with overnight lows between 48° and 66°. The average high for September is 81° 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 New Haven. See also: October | November | December.
