Air District Operations

The Air District is taking steps to ensure Bay Area air quality and public health are protected while the shelter-in-place orders are in effect. Permits for businesses adjusting operations to aid in the public health response will also be expedited. Read more... | en Español

Air Quality Advisory

On Friday and Saturday, smoke from the August Complex Fire may impact the North Bay and parts of the East Bay, causing smoky and hazy skies. There is no Spare the Air Alert in effect and air quality is not expected to be unhealthy. See our hourly air quality data for the most up-to-date information, as well as Press Releases@AirDistrict, and our Wildfire Safety Tips web page.  Sign up for Bay Area Air Alerts.  en Español

About the Air District

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.


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.

Napa County’s climate is also affected by regional Bay Area climate influences.

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

Resource Team

Napa County’s Spare the Air Resource Team promotes ways to reduce air pollution in the local community.

Spare the Air Status
No Wood Burning
Spare the Air Status
  • Saturday,

    No Spare the Air Alert in Effect

Last Updated: 2/14/2019