S
M
T
W
T
F
S
30
88°
78°
31
89°
79°
1
89°
79°
2
88°
78°
3
88°
79°
4
87°
79°
5
87°
77°
6
88°
78°
7
88°
78°
8
87°
77°
9
88°
78°
10
88°
78°
11
87°
79°
12
88°
78°
13
88°
79°
14
87°
78°
15
88°
79°
16
88°
79°
17
87°
78°
18
88°
79°
19
89°
79°
20
87°
77°
21
88°
78°
22
88°
77°
23
87°
76°
24
88°
77°
25
86°
78°
26
88°
79°
27
88°
79°
28
87°
78°
29
88°
79°
30
88°
78°
1
87°
78°
2
87°
77°
3
86°
78°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in San Jose
San Jose's September 2026 forecast shows daily high temperatures ranging from 86° to 89°, with overnight lows between 76° and 79°. The average high for September is 88° with an average low of 78°. 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 San Jose. See also: October | November | December.
