S
M
T
W
T
F
S
30
82°
66°
31
80°
66°
1
81°
62°
2
74°
58°
3
73°
59°
4
73°
58°
5
74°
57°
6
76°
64°
7
80°
64°
8
79°
63°
9
75°
63°
10
78°
64°
11
80°
63°
12
80°
64°
13
79°
64°
14
79°
54°
15
72°
54°
16
69°
55°
17
72°
54°
18
70°
52°
19
69°
53°
20
70°
54°
21
76°
56°
22
76°
59°
23
75°
51°
24
76°
50°
25
71°
50°
26
68°
51°
27
72°
57°
28
73°
57°
29
74°
48°
30
70°
48°
1
66°
53°
2
67°
54°
3
71°
54°
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 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 New Haven. See also: October | November | December.
