S
M
T
W
T
F
S
30
72°
55°
31
70°
57°
1
73°
61°
2
77°
59°
3
79°
57°
4
72°
59°
5
75°
55°
6
75°
55°
7
86°
54°
8
88°
59°
9
97°
68°
10
90°
64°
11
83°
56°
12
77°
57°
13
76°
53°
14
80°
55°
15
80°
55°
16
75°
56°
17
76°
59°
18
75°
60°
19
76°
58°
20
78°
57°
21
80°
59°
22
81°
60°
23
82°
61°
24
78°
56°
25
74°
57°
26
80°
59°
27
74°
55°
28
75°
52°
29
76°
55°
30
80°
59°
1
81°
59°
2
80°
58°
3
80°
58°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in Cupertino
Cupertino's September 2026 forecast shows daily high temperatures ranging from 74° to 83°, with overnight lows between 52° and 61°. The average high for September is 78° 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 Cupertino. See also: October | November | December.
