Monthly weather forecast and climate
Castro Valley, CA

Weather in January

January, like December, is a moderate winter month in Castro Valley, California, with average temperature ranging between max 57°F (13.9°C) and min 43.7°F (6.5°C). In January, the average high-temperature is relatively the same as in December - a still moderate 57°F (13.9°C). Weather in January »

Weather in February

The last month of the winter, February, is also a moderate month in Castro Valley, California, with temperature in the range of an average high of 59.5°F (15.3°C) and an average low of 44.1°F (6.7°C). In Castro Valley, the average high-temperature is relatively the same as in January - a still moderate 59.5°F (15.3°C). Weather in February »

Weather in March

The first month of the spring, March, is an enjoyable month in Castro Valley, California, with average temperature varying between 45°F (7.2°C) and 61.9°F (16.6°C). In March, the average high-temperature is almost the same as in February - an enjoyable 61.9°F (16.6°C). Weather in March »

Weather in April

April, the same as March, is another enjoyable spring month in Castro Valley, California, with temperature in the range of an average high of 66.2°F (19°C) and an average low of 46.4°F (8°C). In April, the average high-temperature is almost the same as in March - a still enjoyable 66.2°F (19°C). Weather in April »

Weather in May

May, the last month of the spring, in Castro Valley, is a pleasant month, with average temperature fluctuating between 49.1°F (9.5°C) and 70.3°F (21.3°C). In Castro Valley, the average high-temperature is relatively the same as in April - an agreeable 70.3°F (21.3°C). Weather in May »

Weather in June

The first month of the summer, June, is a warm month in Castro Valley, California, with temperature in the range of an average low of 53.6°F (12°C) and an average high of 77°F (25°C). In June, the average high-temperature slightly increases, from a pleasant 70.3°F (21.3°C) in May, to a warm 77°F (25°C). Weather in June »

Weather in July

July, the same as June, is a moderately hot summer month in Castro Valley, California, with temperature in the range of an average high of 80.2°F (26.8°C) and an average low of 55.2°F (12.9°C). The warmest month is July, with an average high-temperature of 80.2°F (26.8°C) and an average low-temperature of 55.2°F (12.9°C). Weather in July »

Weather in August

August, the last month of the summer, in Castro Valley, is another warm month, with average temperature fluctuating between 56.5°F (13.6°C) and 79.7°F (26.5°C). In August, the average high-temperature is almost the same as in July - a still warm 79.7°F (26.5°C). Weather in August »

Weather in September

The first month of the autumn, September, is still a warm month in Castro Valley, California, with average temperature fluctuating between 79°F (26.1°C) and 56.3°F (13.5°C). In September, the average high-temperature is relatively the same as in August - a still warm 79°F (26.1°C). Weather in September »

Weather in October

October, the same as September, in Castro Valley, California, is an agreeable autumn month, with average temperature varying between 72.5°F (22.5°C) and 54.3°F (12.4°C). In Castro Valley, the average high-temperature marginally drops, from a moderately hot 79°F (26.1°C) in September, to an agreeable 72.5°F (22.5°C). Weather in October »

Weather in November

The last month of the autumn, November, is also an enjoyable month in Castro Valley, California, with average temperature varying between 63.5°F (17.5°C) and 48.2°F (9°C). In November, the average high-temperature drops, from an agreeable 72.5°F (22.5°C) in October, to an enjoyable 63.5°F (17.5°C). Weather in November »

Weather in December

December, the first month of the winter, in Castro Valley, is also a moderate month, with average temperature ranging between min 43.7°F (6.5°C) and max 55.9°F (13.3°C). December is the coldest month, with an average high-temperature of 55.9°F (13.3°C) and an average low-temperature of 43.7°F (6.5°C). Weather in December »
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FAQ

How many days does it rain in Castro Valley?

Throughout the year, there are 69.2 rainfall days, and 11.1" (282mm) of precipitation is accumulated.

What are the months with the lowest UV index in Castro Valley?

January, February, November and December, with an average maximum UV index of 3, are months with the lowest UV index in Castro Valley.

What is the rainiest month in Castro Valley?

February is the month with the most rainfall. Rain falls for 8.3 days and accumulates 2.28" (58mm) of precipitation.

What is the most humid month in Castro Valley?

With an average relative humidity of 74%, March is the most humid month in Castro Valley, California.

When are the longest days in Castro Valley?

With an average of 14.7h of daylight, June has the longest days of the year.

What is the month with the highest UV index in Castro Valley?

The month with the highest UV index in Castro Valley, California, is June, with an average maximum UV index of 6.

What is the warmest month in Castro Valley?

With an average high-temperature of 80.2°F (26.8°C) and an average low-temperature of 55.2°F (12.9°C), July is the warmest month in Castro Valley, California.

What is the driest month in Castro Valley?

July and August are months with the least rain in Castro Valley when the rain falls for 1.5 days and typically aggregates up to 0.04" (1mm) of rain.

What month has the most sunshine in Castro Valley?

July has the most sunshine of the year in Castro Valley, with an average of 12.1h of sunshine.

What is the least humid month in Castro Valley?

The least humid month is September, with an average relative humidity of 61%.

What is the coldest month in Castro Valley?

December is the coldest month, with an average high-temperature of 55.9°F (13.3°C) and an average low-temperature of 43.7°F (6.5°C).

What is the month with the shortest days in Castro Valley?

December has the shortest days of the year, with an average of 9.6h of daylight.

What is the month with the least sunshine in Castro Valley?

The month with the least sunshine in Castro Valley is December, with an average of 5.9h of sunshine.

Average temperature
Castro Valley, CA

Average temperature - Castro Valley, CA

The warmest month (with the highest average high temperature) is July (80.2°F).
The month with the lowest average high temperature is December (55.9°F).

The month with the highest average low temperature is August (56.5°F).
The coldest months (with the lowest average low temperature) are January and December (43.7°F).

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Average pressure
Castro Valley, CA

Average pressure - Castro Valley, CA

The month with the highest atmospheric pressure is January (30.14").
Months with the lowest atmospheric pressure are June, August and September (29.92").

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Average wind speed
Castro Valley, CA

Average wind speed - Castro Valley, CA

The windiest month (with the highest average wind speed) is May (6.6mph).
The calmest month (with the lowest average wind speed) is November (4.6mph).

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Average humidity
Castro Valley, CA

Average humidity - Castro Valley, CA

The month with the highest relative humidity is March (74%).
The month with the lowest relative humidity is September (61%).

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Average rainfall
Castro Valley, CA

Average rainfall - Castro Valley, CA

The wettest month (with the highest rainfall) is February (2.28").
The driest months (with the least rainfall) are July and August (0.04").

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Average rainfall days
Castro Valley, CA

Average rainfall days - Castro Valley, CA

The month with the highest number of rainy days is March (12.4 days).
The month with the least rainy days is August (0.9 days).

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Average daylight / Average sunshine
Castro Valley, CA

Average daylight / Average sunshine - Castro Valley, CA

The month with the longest days is June (Average daylight: 14.7h).
The month with the shortest days is December (Average daylight: 9.6h).

The month with the most sunshine is July (Average sunshine: 12.1h).
The month with the least sunshine is December (Average sunshine: 5.9h).

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Average sunshine days
Castro Valley, CA

Average sunshine days - Castro Valley, CA

The month with the most sunshine days is August (28.9 days).
The month with the least sunshine days is March (17.3 days).

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Average UV index
Castro Valley, CA

Average UV index - Castro Valley, CA

The month with the highest UV index is June (UV index 6).
Months with the lowest UV index are January, February, November and December (UV index 3).

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Average visibility
Castro Valley, CA

Average visibility - Castro Valley, CA

Months with the highest visibility are January, February, March, April, May, June, July, August, September, October, November and December (6mi).
Months with the lowest visibility are January, February, March, April, May, June, July, August, September, October, November and December (6mi).

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