The temperatures in Sunnyvale in September are comfortable with low of 15°C and and high up to 28°C.
You can expect up to 3 rainy days in Sunnyvale during the month of September.
Our weather forecast can give you a great sense of what weather to expect in Sunnyvale in September 2025.
If you’re planning to visit Sunnyvale in the near future, we highly recommend that you review the 14 day weather forecast for Sunnyvale before you arrive.
Temperatures
28° / 15°
Rainy Days
0
Snowy Days
0
Dry Days
30
Rainfall
6
mm
Sun Hours
11.9
Hrs