Sunnyvale (CA) Weather & Climate: Best Time to Visit
Average temperatures, rainfall, sunshine and the best time to visit Sunnyvale.
Climate overview of Sunnyvale
The climate in Sunnyvale, California, United States of America, is marked by large temperature swings across the seasons, ranging from 27°C (81°F) in September to 15°C (59°F) in December.
The city tends toward dry conditions, with around 323 mm (13 in) of rainfall per year. It does, however, have a distinct dry season from April to November, with warm summers and mild winters. May is the sunniest month, averaging 10.8 hours of sunshine per day.
Sunnyvale Weather by Month
Pick a month to see the average temperature, rainfall and sunshine in Sunnyvale - and find the best time to visit.
Monthly Temperature in Sunnyvale
In Sunnyvale, temperatures differ significantly between summer and winter months. Typically, average maximum daytime temperatures range from a comfortable 27°C (81°F) in September to a moderate 15°C (59°F) in the coolest month, December.
Nights vary from 15°C (59°F) in September to around 5°C (41°F) during the colder months.
Check out our detailed temperature page for more information.
Temperature ranges by month
Rainfall in Sunnyvale
Sunnyvale tends toward drier weather patterns, receiving approximately 323 mm (13 in) of rain per year. The climate in Sunnyvale shows significant variation throughout the year. Expect moderate rainfall in December, the wettest month, with an average of 70 mm (2.8 in) of precipitation over 11 rainy days.
In contrast, the driest month July offers drier and sunnier days, with around 0 mm (0 in) of rainfall over 0 rainy days. For more details, please visit our Sunnyvale Precipitation page.
The mean monthly precipitation over the year, including rain, hail, and snow
The average number of days each month with precipitation
Sunshine Hours in Sunnyvale
For those who appreciate different seasons, Sunnyvale serves as an ideal destination. Expect longer, more sun-filled days in May with an average of 10.8 hours of sunshine daily, and embrace the darker days in December, offering only 5.3 hours of daily sunlight.
Visit our detailed sunshine hours page for more information.
Monthly hours of sunshine
Daily hours of sunshine
Daily percentage of sunshine
Humidity in Sunnyvale by Month
The relative humidity is high throughout the year in Sunnyvale.
The city experiences its highest humidity in January, reaching 80%. In June, the humidity drops to its lowest level at 71%. What does this mean? Read our detailed page on humidity levels for further details.
Relative humidity over the year
Best Time to Visit Sunnyvale
Monthly ratings reflect general weather comfort, based on daytime temperature and rainfall. Swimming and winter conditions are highlighted separately where relevant.
- Best overall: April, May, June, July, August, September and October
- Warmest weather: June, July, August and September
- Most sunshine: April, May, June and July
- Fewer rainy days: May, June, July, August and September
- Seasonal pattern: A distinct dry season from April to November, with warm summers and mild winters
Frequently asked questions about the climate in Sunnyvale
What is the best time to visit Sunnyvale?
April, May, June, July, August, September and October typically offer the most optimal weather in Sunnyvale. In contrast, January, February and December tend to have less optimal conditions. Sunnyvale has a distinct dry season from April to November, with warm summers and mild winters.
What temperatures can I expect in Sunnyvale?
Daytime highs range from 15°C (59°F) in December to 27°C (81°F) in September. Nighttime lows range from 5°C (41°F) to 15°C (59°F). Temperatures vary considerably through the year.
How much rain does Sunnyvale get?
Annual rainfall is around 323 mm (13 in). December is the wettest month with 70 mm (2.8 in), while July is the driest with 0 mm (0 in).
How sunny is Sunnyvale?
Sunnyvale receives around 3,058 hours of sunshine per year. May is the sunniest month with 324 hours, while December is the cloudiest with just 160 hours. Overall, Sunnyvale enjoys abundant sunshine.
Sunnyvale 3-Day Forecast
Sunnyvale (CA) 3-Day Forecast
Sunnyvale on the map
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