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About the Air District

Napa County

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

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

Napa County is nestled in a valley between the Maycamas Mountains in the west and the Vaca Mountains in the east. One Napa County representative sits on the Air District’s Board of Directors.

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

Climate

The mountains bordering Napa Valley block much of the prevailing northwesterly winds throughout the year. Sunshine is plentiful in Napa County, and summertime can be very warm in the valley, particularly in the northern end. Winters are usually mild, with cool temperatures overnight and mild-to-moderate temperatures during the day. Wintertime temperatures tend to be slightly cooler in the northern end of the valley. Winds are generally calm throughout the county. Annual precipitation averages range from about 24 inches in low elevations to more than 40 inches in the mountains. 

Interactive Air Monitoring Stations Map

Air Quality in Napa 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 Napa County, ozone rarely exceeds health standards, but PM2.5 occasionally does reach unhealthy concentrations. There are multiple reasons for PM2.5 exceedances in Napa County.  First, much of the county is wind-sheltered, which tends to trap PM2.5 within the Napa Valley.

Second, much of the area is well north of the moderating temperatures of San Pablo Bay and, as a result, Napa County experiences some of the coldest nights in the Bay Area. This leads to greater fireplace use and, in turn, higher PM2.5 levels. Finally, in the winter easterly winds often move fine-particle-laden air from the Central Valley to the Carquinez Strait and then into western Solano and southern Napa County.

Interactive Air Quality Forecast Map

Spare the Air Status

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Last Updated: 4/21/2017