S
M
T
W
T
F
S
30
91°
65°
31
89°
62°
1
87°
63°
2
89°
65°
3
90°
66°
4
90°
66°
5
89°
64°
6
89°
57°
7
81°
56°
8
80°
56°
9
80°
57°
10
85°
62°
11
86°
61°
12
85°
61°
13
79°
59°
14
78°
62°
15
85°
53°
16
86°
52°
17
76°
52°
18
74°
53°
19
75°
51°
20
74°
51°
21
73°
52°
22
74°
50°
23
74°
50°
24
75°
53°
25
75°
56°
26
79°
57°
27
80°
56°
28
79°
58°
29
81°
49°
30
80°
48°
1
73°
52°
2
72°
46°
3
71°
47°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in Diamond Bay
Diamond Bay's September 2026 forecast shows daily high temperatures ranging from 71° to 91°, with overnight lows between 46° and 66°. The average high for September is 81° with an average low of 56°. 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 Diamond Bay. See also: October | November | December.