S
M
T
W
T
F
S
30
81°
63°
31
71°
63°
1
68°
62°
2
74°
63°
3
74°
67°
4
79°
63°
5
74°
59°
6
70°
59°
7
75°
63°
8
74°
63°
9
75°
64°
10
78°
63°
11
74°
62°
12
76°
61°
13
74°
63°
14
71°
62°
15
72°
57°
16
70°
60°
17
73°
60°
18
66°
57°
19
70°
60°
20
70°
59°
21
68°
58°
22
68°
59°
23
69°
59°
24
69°
58°
25
66°
58°
26
69°
59°
27
71°
60°
28
71°
57°
29
65°
56°
30
66°
56°
1
65°
55°
2
62°
56°
3
63°
55°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in Harwich Center
Harwich Center's September 2026 forecast shows daily high temperatures ranging from 62° to 79°, with overnight lows between 55° and 67°. The average high for September is 71° 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 Harwich Center. See also: October | November | December.