S
M
T
W
T
F
S
30
76°
61°
31
79°
64°
1
81°
64°
2
82°
62°
3
82°
59°
4
81°
64°
5
81°
63°
6
79°
59°
7
75°
61°
8
73°
63°
9
77°
56°
10
76°
55°
11
73°
62°
12
75°
57°
13
79°
61°
14
76°
60°
15
72°
61°
16
72°
54°
17
71°
59°
18
Hist. Avg.
74°
56°
19
Hist. Avg.
73°
56°
20
Hist. Avg.
73°
55°
21
Hist. Avg.
72°
55°
22
Hist. Avg.
72°
54°
23
Hist. Avg.
72°
54°
24
Hist. Avg.
71°
54°
25
Hist. Avg.
71°
53°
26
Hist. Avg.
70°
53°
27
Hist. Avg.
70°
52°
28
Hist. Avg.
70°
52°
29
Hist. Avg.
69°
52°
30
Hist. Avg.
69°
51°
1
Hist. Avg.
69°
51°
2
Hist. Avg.
68°
50°
3
Hist. Avg.
68°
50°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
*Temporarily Unavailable
September Weather in Cos Cob
Cos Cob's September 2026 forecast shows daily high temperatures ranging from 71° to 82°, with overnight lows between 54° and 64°. The average high for September is 77° with an average low of 60°. 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 Cos Cob. See also: October | November | December.
