S
M
T
W
T
F
S
30
78°
60°
31
78°
66°
1
80°
65°
2
75°
70°
3
84°
69°
4
84°
62°
5
77°
57°
6
74°
57°
7
78°
60°
8
76°
57°
9
77°
62°
10
81°
61°
11
81°
58°
12
74°
54°
13
74°
55°
14
78°
56°
15
72°
56°
16
72°
60°
17
74°
53°
18
70°
51°
19
70°
51°
20
71°
54°
21
74°
58°
22
78°
59°
23
78°
59°
24
77°
56°
25
76°
54°
26
76°
55°
27
77°
57°
28
76°
56°
29
75°
53°
30
69°
49°
1
65°
47°
2
68°
52°
3
73°
55°
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 65° to 84°, with overnight lows between 47° and 70°. The average high for September is 75° with an average low of 57°. 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.
