S
M
T
W
T
F
S
30
97°
64°
31
100°
64°
1
100°
68°
2
98°
72°
3
99°
72°
4
98°
72°
5
96°
68°
6
93°
68°
7
92°
67°
8
96°
67°
9
97°
69°
10
92°
64°
11
89°
61°
12
85°
61°
13
86°
60°
14
83°
57°
15
80°
54°
16
83°
59°
17
83°
59°
18
77°
55°
19
79°
58°
20
82°
58°
21
81°
57°
22
79°
57°
23
80°
54°
24
80°
56°
25
81°
56°
26
79°
51°
27
70°
45°
28
70°
44°
29
68°
46°
30
74°
45°
1
70°
49°
2
75°
50°
3
67°
49°
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 67° to 99°, with overnight lows between 44° and 72°. The average high for September is 83° with an average low of 58°. 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.
