San Mateo County, CA Climate

San Mateo County has a mild climate throughout the year. In the summer, temperatures typically reach the mid-70s Fahrenheit and rarely exceed 80 degrees. In the winter, temperatures typically range from the mid-40s to low-60s Fahrenheit. Rainfall is evenly spread out throughout the year, with most of it occurring in late fall and early spring. The county also experiences foggy nights during certain periods, such as in June and July. Overall, San Mateo County has a pleasant climate with minimal temperature fluctuations that make it an ideal place to live or visit.

San Mateo County, California gets 25 inches of rain, on average, per year. The US average is 38 inches of rain per year.

San Mateo County averages 0 inches of snow per year. The US average is 28 inches of snow per year.

On average, there are 260 sunny days per year in San Mateo County. The US average is 205 sunny days.

San Mateo County gets some kind of precipitation, on average, 71 days per year. Precipitation is rain, snow, sleet, or hail that falls to the ground. In order for precipitation to be counted you have to get at least .01 inches on the ground to measure.

Weather Highlights

Summer High: the July high is around 75 degrees
Winter Low: the January low is 42
Rain: averages 25 inches of rain a year
Snow: averages 0 inches of snow a year

Bestplaces Comfort Index

The annual BestPlaces Comfort Index for San Mateo County is 8.4 (10=best), which means it is more comfortable than most places in California.

9.4 Summer - 7.4 Winter

September, August and July are the most pleasant months in San Mateo County, while January and December are the least comfortable months.

Climate	San Mateo, California	United States
	25.1 in.	38.1 in.
	0.0 in.	27.8 in.
	71.3 days	106.2 days
	260 days	205 days
	74.6°	85.8°
	42.1°	21.7°
	8.4	7
	4.9	4.3
	613 ft.	2443 ft.

Climate

YOU SHOULD KNOW

Many people confuse weather and climate but they are different. Weather is the conditions of the atmosphere over a short period of time, and climate is how the atmosphere is over long periods of time.

Weather is how the atmosphere is behaving and its effects upon life and human activities. Weather can change from minute-to-minute. Most people think of weather in terms of temperature, humidity, precipitation, cloudiness, brightness, visibility, wind, and atmospheric pressure.

Climate is the description of the long-term pattern of weather in a place. Climate can mean the average weather for a particular region and time period taken over 30 years. Climate is the average of weather over time.

September is the hottest month for San Mateo County with an average high temperature of 75.1°, which ranks it as one of the coolest places in California. In San Mateo County, there are 5 comfortable months with high temperatures in the range of 70-85°. The most pleasant months of the year for San Mateo County are September, August and July.

In San Mateo County, there are 11.0 days annually when the high temperature is over 90°, which is cooler than most places in California.

January has the coldest nighttime temperatures for San Mateo County with an average of 42.1°. This is warmer than most places in California.

In San Mateo County, there are 7.0 days annually when the nighttime low temperature falls below freezing, which is warmer than most places in California.

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

Humidity in San Mateo County is generally quite low and comfortable. There are few days during the summer when the humidity becomes unpleasant. The most humid months (but still comfortable) are August, July and September.

February is the wettest month in San Mateo County with 4.9 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 25.1 inches in San Mateo County means that it is wetter than most places in California.

January is the rainiest month in San Mateo County with 11.2 days of rain, and July is the driest month with only 0.9 rainy days. There are 71.3 rainy days annually in San Mateo County, which is rainier than most places in California. The rainiest season is Spring when it rains 46% of the time and the driest is Autumn with only a 5% chance of a rainy day.

There is rarely any recorded snowfall in San Mateo County, ranking it as one of the least snowy places in California. Any measurable snowfall is a rare occurance in San Mateo County.

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