Sunnyvale Weather in September

September in Sunnyvale averages 27°C (81°F) during the day and 14°C (57°F) at night. With only 2.8 mm (0.1 in) of rainfall expected on average, it's a largely dry month.

Rainfall in Sunnyvale in September

Historically, approximately a single day this month are expected to have rain, averaging 2.8 mm (0.1 in). If rain does fall, it tends to be very light and barely worth getting out an umbrella for.

Temperature in Sunnyvale in September

The temperature in Sunnyvale in September is perfect. Daytime highs reach 27°C (81°F), with nights dropping to 14°C (57°F). Experience the summer season in September. The days can feel warmer than the evenings, so packing for both parts of the day is a good idea. With overnight lows of 14°C (57°F), evenings can feel noticeably cooler than the daytime. An extra layer is a good idea, though the cool air makes for a good night's sleep. It's the warmest month of the year on average, so summer clothing is the way to go.

Sunshine in Sunnyvale in September

The days are predominantly sunny, with an estimated total of around 270 hours of sunshine. These sun-filled days are perfect for playing sports, visiting parks, or going for a bike ride.

If your ideal day consists of dry skies and pleasant temperatures, April, May, June, July, August, September and October typically offer the best circumstances for Sunnyvale.

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• January
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For a detailed overview over the year and the best time to visit the United States of America, check out our Sunnyvale's climate page.

Sunnyvale Temperature in September

Min Temperature 14°C (57°F)  

Max Temperature 27°C (81°F)  

Chance of Rain 3%  

Precipitation 2.8 mm (0.1 in)  

Rainy days a single day  

Humidity 73% *  

Sunshine 270 hours *  

Percentage Sunshine 73% *  

* Data from: San Francisco, the United States of America (41 KM, 25 Miles).

What to Wear in Sunnyvale in September

Warm weather calls for comfortable, breathable clothing in September. Cotton t-shirts, shorts, light dresses, and sandals are perfect. You might still want a light layer for evenings or air-conditioned places (for example buses). Almost no rain is expected, so no need to bring rain gear. Don't forget sun protection, sunglasses, sunscreen, and a hat. These are all good ideas with this much sunshine.

What To Do in Sunnyvale in September

We rated the following activities from 1 (least suitable) to 10 (best) to do.

Swimming

10/10

Cycling

8/10

Walking

8/10

Barbeque

10/10

Camping

10/10

Outdoor sports

8/10

Select a Month

Check the conditions for any month of the year.

• January
• February
• March
• April

• May
• June
• July
• August

• September
• October
• November
• December

For a detailed overview over the year and the best time to visit the United States of America, check out our Sunnyvale's climate page.

More climate data for Sunnyvale

Temperature Rainfall Sunshine Humidity

See the full Sunnyvale climate overview or explore weather in the United States of America.