S
M
T
W
T
F
S
30
75°
61°
31
78°
66°
1
80°
67°
2
80°
66°
3
76°
63°
4
75°
60°
5
74°
59°
6
73°
58°
7
75°
64°
8
79°
59°
9
72°
56°
10
73°
55°
11
76°
52°
12
70°
55°
13
71°
55°
14
69°
54°
15
71°
55°
16
72°
54°
17
71°
53°
18
75°
55°
19
70°
52°
20
70°
51°
21
68°
51°
22
69°
52°
23
71°
55°
24
75°
52°
25
75°
56°
26
74°
57°
27
68°
53°
28
67°
53°
29
73°
52°
30
71°
48°
1
66°
52°
2
71°
57°
3
72°
46°
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 80°, with overnight lows between 46° and 67°. The average high for September is 73° with an average low of 56°. 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.
