Languages:
English

popular searches:

Refinery Rules, Climate, Asbestos
Public Data Center
Air Monitoring Data
Contact Us
  1. Air District
  2. About the Air District
  3. In Your Community
  4. San Mateo County
About the Air District

San Mateo County

About the Air District
  1. Air District
  2. About the Air District
  3. In Your Community
  4. 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
  • Air District lifts air quality advisory for wildfire smoke for Monday
    July 14, 2025

    The Air District is lifting an air quality advisory for the Bay Area due to wildfire smoke that was originally scheduled to last through today, Monday, July 14. Over the weekend, smoke from the Butler and Green wildfires had been moving down the Sacramento Valley and impacting air quality in portions of the Bay Area. However, as of Monday morning, the Bay Area is experiencing strong onshore winds, and smoke has remained mostly outside of the region. Air quality has been in the Good Air Quality Index category. Moderate onshore winds are expected to continue into Tuesday, keeping the smoke outside of the Bay Area. As the week progresses, these onshore winds will turn southerly in northern California, and this also is expected to keep the smoke from moving towards our region.

    Learn More
  • Air District extends air quality advisory for wildfire smoke through Monday
    July 12, 2025

    The Air District is extending an air quality advisory for the Bay Area due to wildfire smoke from fires in northern Sacramento Valley through Monday, July 14. Smoke from the Butler and Green wildfires is still moving down the Sacramento Valley and is expected to continue to impact air quality in portions of the Bay Area on Sunday and Monday. Areas that are expected to be most impacted will be parts of the North Bay and East Bay and higher elevation locations. Conditions can change rapidly and the amount and location of smoke at ground level is hard to predict. The public can check for real-time smoke pollution levels in their local area with the U.S. EPA’s Fire and Smoke Map.  Smoky, hazy skies may be visible, the smell of smoke is possible and air quality may become unhealthy at times on Sunday and Monday. 

    Learn More
  • Air District extends air quality advisory for wildfire smoke through Saturday
    July 11, 2025

    The Air District is extending an air quality advisory for the Bay Area due to wildfire smoke from fires in northern Sacramento Valley through Saturday, July 12. Smoke from the Butler and Green wildfires is moving down the Sacramento Valley and is expected to continue to impact air quality in portions of the Bay Area on Saturday. Conditions can change rapidly and the amount and location of smoke at ground level is hard to predict. The public can check for real-time smoke pollution levels in their local area with the U.S. EPA’s Fire and Smoke Map. Smoky, hazy skies may be visible, the smell of smoke is possible and air quality may become unhealthy at times on Saturday. 

     
    Learn More
  • Air District issues air quality advisory for wildfire smoke for Thursday and Friday
    July 10, 2025

    The Air District is issuing an air quality advisory for the Bay Area due to wildfire smoke from fires in northern Sacramento Valley for today, Thursday, July 10, and Friday, July 11. Smoke from the Butler and Green wildfires has been moving down the Sacramento Valley and is expected to impact air quality in the eastern portion of the Bay Area down to Santa Clara Valley on Thursday and Friday. Conditions can change rapidly and the amount and location of smoke at ground level is hard to predict. The public can check for real-time smoke pollution levels in their local area with the U.S. EPA’s Fire and Smoke Map. Smoky, hazy skies may be visible, the smell of smoke is possible and air quality may become unhealthy at times on Thursday and Friday. 

     

    Learn More
Other News Articles

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. 

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

Spare the Air Status

Return

Last Updated: 4/21/2017