2025 Compare Climate & Weather:
Castro Valley, CA vs Clearlake, CA

Highlights

On average, there are 262 sunny days per year in Clearlake. Castro Valley averages 261 sunny days per year. The US average is 205 sunny days.

Clearlake, California gets 33 inches of rain, on average, per year. Castro Valley, California gets 21.3 inches of rain, on average, per year. The US average is 38.1 inches of rain per year.

Clearlake averages 0.9 inches of snow per year. Castro Valley averages 0 inches of snow per year. The US average is 27.8 inches of snow per year.

Weather Highlights

Clearlake, California
Summer High: the July high is around 91 degrees
Winter Low: the January low is 33.2
Rain: averages 33 inches of rain a year
Snow: averages 0.9 inches of snow a year

Castro Valley, California
Summer High: the July high is around 75.6 degrees
Winter Low: the January low is 41.6
Rain: averages 21.3 inches of rain a year
Snow: averages 0 inches of snow a year

BestPlaces Comfort Index

The annual BestPlaces Comfort Index for Clearlake is 7.9 (10=best), which means it is less comfortable than most places in California.

The annual BestPlaces Comfort Index for Castro Valley is 8.6 (10=best), which means it is more comfortable than most places in California.

Today's Weather - Castro Valley, CA

65°F

Today's Weather - Clearlake, CA

75°F

Average Monthly High / Low (°F)

Hot, Freezing, Rainy, Snowy Days: Castro Valley / Clearlake

September is the hottest month for Castro Valley with an average high temperature of 77.3°, which ranks it as cooler than most places in California. In Castro Valley, there are 6 comfortable months with high temperatures in the range of 70-85°. The most pleasant months of the year for Castro Valley are September, August and July.

July is the hottest month for Clearlake with an average high temperature of 91.0°, which ranks it as about average compared to other places in California. In Clearlake, there are 3 comfortable months with high temperatures in the range of 70-85°. The most pleasant months of the year for Clearlake are May, October and June.

January has the coldest nighttime temperatures for Castro Valley with an average of 41.6°. This is warmer than most places in California.

January has the coldest nighttime temperatures for Clearlake with an average of 33.2°. This is colder than most places in California.

In Castro Valley, there are 12.0 days annually when the high temperature is over 90°, which is cooler than most places in California.

In Clearlake, there are 55.9 days annually when the high temperature is over 90°, which is about average compared to other places in California.

In Castro Valley, there are 3.7 days annually when the nighttime low temperature falls below freezing, which is warmer than most places in California.

In Clearlake, there are 56.2 days annually when the nighttime low temperature falls below freezing, which is colder than most places in California.

In Castro Valley, there are 0.0 days annually when the nighttime low temperature falls below zero°, which is about average compared to other places in California.

In Clearlake, there are 0.0 days annually when the nighttime low temperature falls below zero°, which is about average compared to other places in California.

February is the wettest month in Castro Valley with 4.0 inches of rain, and the driest month is July with 0.0 inches. The wettest season is Spring with 55% of yearly precipitation and 1% occurs in Autumn, which is the driest season. The annual rainfall of 21.3 inches in Castro Valley means that it is wetter than most places in California.


January is the wettest month in Clearlake with 6.7 inches of rain, and the driest month is July with 0.0 inches. The wettest season is Spring with 58% of yearly precipitation and 1% occurs in Autumn, which is the driest season. The annual rainfall of 33.0 inches in Clearlake means that it is wetter than most places in California.

December is the rainiest month in Castro Valley with 11.6 days of rain, and July is the driest month with only 0.1 rainy days. There are 66.0 rainy days annually in Castro Valley, which is rainier than most places in California. The rainiest season is Spring when it rains 51% of the time and the driest is Autumn with only a 2% chance of a rainy day.

January is the rainiest month in Clearlake with 10.9 days of rain, and July is the driest month with only 0.1 rainy days. There are 66.0 rainy days annually in Clearlake, which is rainier than most places in California. The rainiest season is Spring when it rains 47% of the time and the driest is Autumn with only a 3% chance of a rainy day.

There is rarely any recorded snowfall in Castro Valley, ranking it as one of the least snowy places in California.

An annual snowfall of 0.9 inches in Clearlake means that it is snowier than most places in California.

Any measurable snowfall is a rare occurance in Castro Valley.

January is the snowiest month in Clearlake with 0.5 inches of snow, and 1 month of the year have significant snowfall.