S
M
T
W
T
F
S
30
80°
58°
31
79°
57°
1
80°
58°
2
81°
58°
3
82°
57°
4
82°
59°
5
81°
59°
6
83°
60°
7
83°
60°
8
82°
59°
9
82°
59°
10
77°
58°
11
76°
60°
12
81°
60°
13
82°
61°
14
83°
60°
15
82°
59°
16
81°
58°
17
79°
59°
18
81°
59°
19
81°
60°
20
75°
53°
21
75°
52°
22
Hist. Avg.
79°
52°
23
Hist. Avg.
79°
52°
24
Hist. Avg.
79°
52°
25
Hist. Avg.
79°
52°
26
Hist. Avg.
79°
52°
27
Hist. Avg.
79°
52°
28
Hist. Avg.
79°
52°
29
Hist. Avg.
78°
51°
30
Hist. Avg.
78°
51°
1
Hist. Avg.
78°
51°
2
Hist. Avg.
78°
51°
3
Hist. Avg.
78°
51°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
*Temporarily Unavailable
September Weather in Cupertino
Cupertino's September 2026 forecast shows daily high temperatures ranging from 75° to 83°, with overnight lows between 52° and 61°. The average high for September is 80° 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.
