About the Air District

San Mateo County

Learn about San Mateo County - its climate, potential air pollution concerns, and current air quality. You can also view upcoming Air District events in San Mateo County and read about local efforts to improve air quality.

Latest News
  • Sep
    20

    September 20, 2022

    Air District launches California’s first Clean Air Center in San Francisco

    The Air District, California Air Resources Board and San Francisco Department of Emergency Management announced today the launch of the state’s first Clean Air Center in the Bayview Hunters Point neighborhood in San Francisco. In the coming weeks, more than 300 Clean Air Centers will be available throughout the Bay Area, when air quality is poor due to wildfires.

  • Sep
    14

    September 14, 2022

    Air District abatement order to shut down Green Sage diesel generators held immediately enforceable by Alameda Superior Court judge

    The Air District received a ruling from an Alameda County Superior Court judge yesterday finding that an abatement order to shut down diesel generators at the Green Sage cannabis facilities in Oakland is immediately enforceable by further order of the court.

  • Sep
    10

    September 10, 2022

    Air District extends air quality advisory through Sunday

    The Air District is extending an air quality advisory for wildfire smoke through tomorrow, Sunday, September 11. Smoke from wildfires in California, Oregon and Washington are expected to continue to impact the Bay Area tomorrow. Isolated pockets of elevated air pollution levels are possible; however, pollution levels are not expected to exceed the national 24-hour standard. A Spare the Air Alert is not in effect and air quality is not expected to be unhealthy. Smoky, hazy skies may be visible and the smell of smoke may be present.

  • Sep
    9

    September 9, 2022

    Air District extends air quality advisory through Saturday

    The Air District is extending an air quality advisory for wildfire smoke through tomorrow, Saturday, September 10. Smoke from wildfires in California and Oregon is expected to continue to impact the Bay Area through Saturday, but pollutant levels are not expected to exceed the national 24-hour health standard. A Spare the Air Alert is not in effect. Smoky, hazy skies may be visible and the smell of smoke may be present. 

San Mateo County lies in the middle of the San Francisco Peninsula, south of San Francisco County, and north of Santa Clara and Santa Cruz counties. It is bounded by the Pacific Ocean to the west and San Francisco Bay to the east. Two San Mateo County representatives sit on the Air District’s Board of Directors.

Climate

Cool, foggy weather is prevalent along the western coast of the peninsula, particularly during the summer. Summertime average daily temperatures are moderate along the west coast and warm in the county’s east side. In the winter, average daily temperatures across the county range from mild to moderate. Winds are mild, with the highest wind speeds focused along the western coast. Rainfall averages about 20 to 25 inches per year at lower elevations and up to 36 inches in the Santa Cruz Mountains.

San Mateo County's climate is also affected by regional Bay Area climate influences.

Interactive Air Monitoring Stations Map

Air Quality in San Mateo County

Ozone and fine particle pollution, or PM2.5, are the major regional air pollutants of concern in the San Francisco Bay Area. Ozone is primarily a problem in the summer, and fine particle pollution in the winter.

In San Mateo County, ozone almost never exceeds health standards, and PM2.5 exceeds the national standard only on about one day each year. San Mateo County frequently receives fresh marine air from the Pacific Ocean, which passes over the coastal hills. In winter, PM2.5 may be transported into San Mateo County from other parts of the Bay Area, adding to wood smoke, which may lead to elevated concentrations, but these are rarely high enough to exceed health standards.

Interactive Air Quality Forecast Map

Resource Team

San Mateo County's Spare the Air Resource Team promotes ways to reduce air pollution in the local community.

Spare the Air Status

Last Updated: 2/14/2019