About the Air District

Alameda County

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

Alameda County lies east of the San Francisco Bay, bounded by Contra Costa Bay to the north, San Joaquin County to the east, and Santa Clara County to the south. Four representatives sit on the Air District’s Board of Directors.

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Along the county’s western coast, temperatures are moderated by the bay, which can act as a heat source during cold weather, or cool the air by evaporation during warm weather. It is generally sunnier farther from the coast, although partly cloudy skies are common throughout the summer. Average summer temperatures are mild overnight and moderate during the day. Winter temperatures are cool overnight and mild during the day. Highest temperatures are more common inland. Wind speeds vary throughout the county, with the strongest gusts along the western coast, often aided by dominant westerly winds and a bay-breeze effect. Rainfall totals average about 14 to 23 inches per year, with the highest totals in the northern end of the county and atop the Oakland-Berkeley hills. 

Interactive Air Monitoring Stations Map

Air Quality in Alameda 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 Alameda County west of the East Bay hills, ozone rarely exceeds health standards because the area is adjacent to San Francisco Bay, which tends to keep temperatures well below prime levels for ozone formation.  PM2.5 is a more significant issue in this region due to cool winter nights with light winds, wood smoke, and occasional pollution transport from the Livermore Valley to the east.

Eastern Alameda County has the highest ozone levels in the Bay Area, with summer afternoon temperatures frequently approaching triple digits, spurring ozone levels to exceed health standards. In winter, PM2.5 can be transported westward through the Altamont Pass from the Central Valley where it adds to wood smoke levels, causing health standards to be exceeded.

Interactive Air Quality Forecast Map

Spare the Air Status

Last Updated: 4/21/2017