S
M
T
W
T
F
S
30
86°
57°
31
78°
56°
1
77°
57°
2
77°
62°
3
78°
57°
4
79°
64°
5
83°
63°
6
84°
56°
7
81°
56°
8
76°
55°
9
75°
54°
10
75°
61°
11
77°
54°
12
78°
55°
13
74°
54°
14
73°
60°
15
77°
61°
16
80°
52°
17
81°
51°
18
71°
50°
19
70°
52°
20
70°
52°
21
71°
53°
22
69°
51°
23
68°
55°
24
70°
56°
25
70°
55°
26
75°
57°
27
75°
50°
28
76°
48°
29
68°
48°
30
68°
54°
1
67°
55°
2
72°
53°
3
71°
48°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in Old Greenwich
Old Greenwich's September 2026 forecast shows daily high temperatures ranging from 67° to 86°, with overnight lows between 48° and 64°. The average high for September is 75° with an average low of 55°. 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 Old Greenwich. See also: October | November | December.
