Castro Valley (CA) Weather and Climate: A Comprehensive Guide
Temperatures see a moderate degree of fluctuation,
transitioning from warm conditions
to mild.
It receives mid-range precipitation levels.
Let’s explore the climate details in depth to provide you with a complete overview.
Average maximum day and minimum night temperature
The weather in Castro Valley changes moderately throughout the year, offering enough variation to appreciate each season. Average maximum daytime temperatures range from a comfortable 25°C in September, the warmest time of the year, to a moderate 14°C during cooler months like December.
At night, temperatures typically drop to an average of around 5°C during these months. Check out our detailed temperature page for more information.Temperature ranges by month
Precipitation and rainy days
Generally, Castro Valley experiences moderate precipitation patterns, averaging 512 mm yearly. Significant seasonal changes in precipitation occur throughout the year. During the wetter season, December receives high rainfall, averaging 111 mm of precipitation, recorded across 13 rainy days. In contrast, the drier season, August brings less rainfall, with 0.1 mm over 0 rainy days. For more details, please visit our Castro Valley Precipitation page.The mean monthly precipitation over the year, including rain, hail and snow
The average number of days each month with precipitation
Sunshine over the year
Seasonal changes in sunshine hours are quite dramatic in Castro Valley. While May receives considerable daily sunshine with up to 10.8 hours, December marks the darkest time of the year, where sunshine is scarce with only 5.3 hours of sunlight per day. Visit our detailed sunshine hours page for more information.Monthly hours of sunshine
Daily hours of sunshine
Daily percentage of sunshine
Average humidity
The relative humidity is high throughout the year in Castro Valley.
The city experiences its highest humidity in January, reaching 80%. In June, the humidity drops to its lowest level at 71%. Explore our detailed page on humidity levels for further details.
Relative humidity over the year
broken clouds and no rain partly cloudy and rain broken clouds and no rainForecast for Castro Valley (CA)
2 m/s
5 m/s
3 m/s
The best time of year to visit Castro Valley in the United States of America
During the months of May, June, July, August, September and October you are most likely to experience good weather with pleasant average temperatures that fall between 20°C and 26°C.Other facts from our historical weather data:
Yes, the months of May, June, July, August and September are very dry.
September has an average maximum temperature of 25°C and is the warmest month of the year.
The coldest month is December with an average maximum temperature of 14°C.
December tops the wettest month list with 111 mm of rainfall.
August is the driest month with 0 mm of precipitation.
May is the sunniest month with an average of 324 hours of sunshine.
No idea where to travel to this year? We have a tool that recommends destinations based on your ideal conditions. Find out where to go with our weather planner.
