S
M
T
W
T
F
S
30
83°
56°
31
81°
66°
1
90°
72°
2
73°
69°
3
89°
69°
4
86°
73°
5
81°
65°
6
80°
60°
7
80°
59°
8
83°
54°
9
87°
64°
10
88°
73°
11
82°
62°
12
82°
57°
13
82°
69°
14
76°
57°
15
75°
51°
16
82°
56°
17
83°
68°
18
83°
68°
19
75°
61°
20
73°
60°
21
69°
54°
22
61°
50°
23
60°
52°
24
62°
46°
25
66°
50°
26
69°
47°
27
71°
45°
28
70°
46°
29
71°
48°
30
70°
49°
1
70°
48°
2
71°
46°
3
66°
51°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in Mainland
Mainland's September 2026 forecast shows daily high temperatures ranging from 60° to 75°, with overnight lows between 45° and 61°. The average high for September is 68° with an average low of 50°. 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 Mainland. See also: October | November | December.
