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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 allocates $1.3 million to improve air quality in West Contra Costa County schools
    June 04, 2025

    The Air District's Board of Directors approved allocating $4 million in Community Air Protection Incentives funding to support home and school air filtration programs in Bay Area communities at their June 4 meeting. As part of this initiative, the Air District Board authorized up to $1.3 million of upgrades in public schools in Richmond, North Richmond, San Pablo, and Tara Hills. An additional $1.7 million will be used to expand air filtration upgrades in schools in Bayview-Hunters Point in San Francisco, and $1 million will be allocated to the Air District’s Home Air Filtration program.

    Learn More
  • Air District extends air quality advisory for wildfire smoke through Thursday
    June 04, 2025

    The Air District is extending an air quality advisory due to wildfire smoke from Canadian wildfires in the Bay Area through Thursday, June 5. Smoke from various Canadian wildfires in Alberta, Saskatchewan, and Manitoba is expected to impact air quality in the Bay Area through Thursday. Conditions can change rapidly and the amount and location of smoke at ground level are 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 through Thursday, June 5.

    Learn More
  • Air District extends air quality advisory for wildfire smoke through Wednesday
    June 03, 2025

    The Air District is extending an air quality advisory due to wildfire smoke from Canadian wildfires in the Bay Area through Wednesday, June 4. Smoke from various Canadian wildfires in Alberta, Saskatchewan and Manitoba is expected to impact air quality in the Bay Area through Wednesday. Conditions can change rapidly and the amount and location of smoke at ground level are 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 through Wednesday, June 4.

    Learn More
  • Air District issues air quality advisory for wildfire smoke for Monday and Tuesday
    June 02, 2025

    The Air District is issuing an air quality advisory due to wildfire smoke from Canadian wildfires in the Bay Area for Monday, June 2 and Tuesday, June 3. Smoke from various Canadian wildfires in Alberta, Saskatchewan, and Manitoba is expected to impact air quality in parts of the Bay Area on Monday and Tuesday. 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 on Monday and Tuesday.

    Learn More
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

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Last Updated: 4/21/2017