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Sunnyvale Weather by Month
Average temperatures, rainfall and humidity for Sunnyvale, United States, month by month, built from OpenWeather’s historical records. Use it to see what a typical Sunnyvale month looks like before you travel — then check the live Sunnyvale forecast for the days ahead.
Warmest month
July
28°C average high
Coolest month
January
7°C average low
Wettest month
December
94 mm of rain
Driest month
July
7 mm of rain
Average temperature and rainfall in Sunnyvale by month
Averages of the daily highs and lows recorded in each month, with total rainfall, mean humidity and mean wind speed.
| Month | Avg high | Avg low | Record low / high | Rainfall | Humidity | Wind |
|---|---|---|---|---|---|---|
| January | 16°C | 7°C | -5°C / 25°C | 82 mm | 76% | 9 km/h |
| February | 17°C | 7°C | -3°C / 26°C | 82 mm | 72% | 10 km/h |
| March | 19°C | 8°C | -1°C / 33°C | 66 mm | 71% | 11 km/h |
| April | 21°C | 9°C | 0°C / 33°C | 35 mm | 68% | 12 km/h |
| May | 23°C | 11°C | 3°C / 36°C | 26 mm | 67% | 13 km/h |
| June | 27°C | 13°C | 5°C / 38°C | 18 mm | 67% | 11 km/h |
| July | 28°C | 14°C | 8°C / 38°C | 7 mm | 69% | 11 km/h |
| August | 28°C | 15°C | 8°C / 39°C | 19 mm | 71% | 10 km/h |
| September | 27°C | 14°C | 7°C / 42°C | 29 mm | 68% | 10 km/h |
| October | 24°C | 12°C | 2°C / 39°C | 27 mm | 66% | 8 km/h |
| November | 19°C | 9°C | -2°C / 27°C | 42 mm | 72% | 8 km/h |
| December | 15°C | 7°C | -3°C / 29°C | 94 mm | 77% | 8 km/h |
Best time to visit Sunnyvale
The most comfortable time to visit Sunnyvale is generally May to June and October, balancing mild daytime temperatures against the driest stretch of the year. The city has a moderate seasonal swing and rain concentrates around December, totalling about 526 mm a year.
Travellers who prefer heat should aim for July, when highs average 28°C. December is the month to avoid if rain would spoil your plans — it averages 94 mm, roughly 14× the rainfall of the driest month (July).
Source: OpenWeather historical and statistical weather data. Values are long-term averages, not a forecast — see the Sunnyvale forecast for what is happening now.