S
M
T
W
T
F
S
30
80°
58°
31
77°
66°
1
74°
63°
2
73°
63°
3
80°
67°
4
83°
68°
5
79°
62°
6
71°
58°
7
79°
52°
8
79°
56°
9
80°
59°
10
85°
68°
11
77°
58°
12
76°
52°
13
76°
66°
14
74°
64°
15
69°
52°
16
75°
54°
17
78°
68°
18
81°
56°
19
68°
59°
20
69°
60°
21
69°
55°
22
64°
51°
23
66°
54°
24
69°
57°
25
71°
56°
26
71°
52°
27
73°
58°
28
72°
57°
29
71°
57°
30
72°
52°
1
66°
52°
2
73°
56°
3
66°
55°
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 64° to 81°, with overnight lows between 51° and 68°. The average high for September is 71° 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.
