Castro Valley (CA) Sunshine Hours by Month

To truly understand a climate, we must look at its sunshine. This page shows the total number of hours of direct sunlight per month and the average hours per day in Castro Valley, California, United States of America. These values are calculated using 30 years of data (1990–2020) to ensure accuracy.

Monthly hours of sunshine

If you're visiting Castro Valley, timing is key. In May, you can enjoy up to 324 hours of sunshine, while the shorter days of December provide just 160 hours. The total annual amount of sun is 3058 hours.

Daily hours of sunshine

This means the city can be enjoyed more throughout the sunniest month of May under a blue sky, with approximately 10.8 hours of sunshine daily. In contrast, the city experiences much darker days in December, with only 5.3 hours of sunlight per day.

Average percent of sunshine

On average the sun shines 78% of the time during the day in April, the highest percentage of any month. December has the lowest percentage at 54%.

Castro Valley enjoys an average of 3058 hours of sunshine annually. Let’s compare this with some popular tourist destinations:

Athens, Greece, enjoys 2769 hours of sunshine each year, making it one of the sunniest destinations in the Mediterranean region.

In contrast, Brussels, Belgium, receives only about 1590 hours of sunshine per year, known for its frequently overcast and rainy skies.

Osaka, Japan, experiences 2010 hours of sunshine annually, with bright, sunny weather in spring and autumn.

Melbourne, Australia, has 2380 hours of sunshine annually, with its famous “four seasons in a day” weather pattern.

December, Castro Valley’s wettest month, receives 4.2 mm (0.2 in) of rainfall and has a maximum daytime temperature of 14°C (57°F). During the driest month August you can expect a temperature of 24°C (75°F).

For more detailed insights into the city’s temperatures, check out our Temperature page. To explore more about precipitation patterns, visit our Castro Valley Precipitation page.