S
M
T
W
T
F
S
30
85°
54°
31
86°
53°
1
85°
50°
2
83°
50°
3
81°
54°
4
82°
50°
5
85°
51°
6
86°
52°
7
80°
50°
8
83°
53°
9
80°
53°
10
83°
47°
11
82°
49°
12
84°
52°
13
80°
50°
14
76°
48°
15
77°
46°
16
Hist. Avg.
77°
47°
17
Hist. Avg.
77°
47°
18
Hist. Avg.
76°
46°
19
Hist. Avg.
76°
46°
20
Hist. Avg.
75°
46°
21
Hist. Avg.
75°
45°
22
Hist. Avg.
74°
45°
23
Hist. Avg.
74°
44°
24
Hist. Avg.
74°
44°
25
Hist. Avg.
73°
43°
26
Hist. Avg.
73°
43°
27
Hist. Avg.
72°
42°
28
Hist. Avg.
72°
42°
29
Hist. Avg.
71°
42°
30
Hist. Avg.
71°
41°
1
Hist. Avg.
70°
41°
2
Hist. Avg.
70°
40°
3
Hist. Avg.
70°
40°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
*Temporarily Unavailable
September Weather in Sunnyvale
Sunnyvale's September 2026 forecast shows daily high temperatures ranging from 76° to 86°, with overnight lows between 46° and 54°. The average high for September is 82° with an average low of 51°. 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 Sunnyvale. See also: October | November | December.
