S
M
T
W
T
F
S
30
76°
59°
31
76°
60°
1
77°
60°
2
76°
59°
3
76°
61°
4
77°
61°
5
76°
59°
6
77°
58°
7
82°
55°
8
80°
54°
9
78°
53°
10
77°
54°
11
76°
55°
12
77°
54°
13
76°
55°
14
77°
60°
15
76°
60°
16
78°
59°
17
82°
60°
18
82°
60°
19
81°
59°
20
82°
60°
21
82°
59°
22
81°
59°
23
78°
58°
24
78°
57°
25
75°
59°
26
79°
58°
27
81°
58°
28
80°
55°
29
80°
57°
30
79°
58°
1
80°
59°
2
82°
58°
3
80°
60°
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 75° to 82°, with overnight lows between 53° and 61°. The average high for September is 79° with an average low of 58°. 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.
