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About the Air District

Santa Clara County

About the Air District
  1. Air District
  2. About the Air District
  3. In Your Community
  4. Santa Clara County

Learn about Santa Clara County - its climate, potential air pollution concerns, and current air quality. You can also view upcoming Air District events in Santa Clara 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.

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  • 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. 

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  • 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. 

     
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  • 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. 

     

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Other News Articles

Santa Clara County is south of the San Francisco Bay, with San Mateo and Alameda counties bordering it to the north, Santa Cruz County to the west, San Benito County to the south, and Stanislaus and Merced counties to the east. Four Santa Clara County representatives sit on the Air District’s Board of Directors.

Climate

During the summer, mostly clear skies result in warm daytime temperatures and cool nights. Winter temperatures are mild, except for very cool but generally frost-less mornings. 

Further inland where the moderating effect of the bay is not as strong, temperature extremes are greater. Wind patterns are influenced by local terrain, with a northwesterly sea breeze typically developing during the daytime. Winds are usually stronger in the spring and summer. Rainfall amounts are modest, ranging from 13 inches in the lowlands to 20 inches in the hills. 

Interactive Air Monitoring Stations Map

Air Quality in Santa Clara 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.

Most of Santa Clara County is well south of the cooler waters of the San Francisco Bay and far from the cooler marine air which usually reaches across San Mateo County in summer.  Ozone frequently forms on hot summer days when the prevailing seasonal northerly winds carry ozone precursors southward across the county, causing health standards to be exceeded.

Santa Clara County experiences many exceedances of the PM2.5 standard each winter. This is due to the high population density, wood smoke, industrial and freeway traffic, and poor wintertime air circulation caused by extensive hills to the east and west that block wind flow into the region.

Interactive Air Quality Forecast Map

Spare the Air Status

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Last Updated: 4/21/2017