The Air District is lifting an air quality advisory for wildfire smoke that was originally scheduled to last through tomorrow, Wednesday, August 27.
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Contra Costa County
Learn about Contra Costa County - its climate, potential air pollution concerns, and current air quality. You can also view upcoming Air District events in Contra Costa County and read about local efforts to improve air quality.
Contra Costa County lies east of the San Pablo Bay, bounded by Alameda County to the south, San Joaquin County to the east, and Solano and Sacramento counties to the north. Four representatives sit on the Air District’s Board of Directors.
Latest News
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Air District awards $13.3 million to SamTrans toward the installation of new zero-emission bus charging infrastructureAugust 26, 2025
The Air District has announced a $13.3 million grant to the San Mateo County Transit District toward the installation of new high-capacity electric bus charging infrastructure at its San Carlos facility. This SamTrans project will help accelerate the transition of the SamTrans bus fleet to zero-emission technology and improve air quality in communities most affected by air pollution.
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The Air District is extending an air quality advisory due to wildfire smoke from the Pickett Fire through Wednesday, August 27. Smoke from the Pickett Fire in Napa County is expected to impact Napa, Solano and Sonoma counties through Wednesday. 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, and the smell of smoke is possible.
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The Air District is extending an air quality advisory due to wildfire smoke from the Pickett Fire through Monday, August 25. Smoke from the Pickett Fire in Napa County is expected to impact Napa, Solano and Sonoma counties through Monday. 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, and the smell of smoke is possible.
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Upcoming Events
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Other News Articles
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8/18/2025 Air District directs Crown Hill Materials to cease operating unpermitted concrete batch plant
August 18, 2025
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8/14/2025 Air District files lawsuit against Acme Fill Corporation for illegal landfill emissions
August 14, 2025
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8/12/2025 Air District issues air quality advisory for wildfire smoke for Tuesday
August 12, 2025
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8/11/2025 Air District reaches agreement with Argent Materials to resolve air quality violations
August 11, 2025
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7/30/2025 Deadline to apply for the Air District’s Clean HEET program extended
July 30, 2025
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7/28/2025 Air District awards $3.5 million in second cycle of James Cary Smith Community Grant Program
July 28, 2025
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7/23/2025 Air District urges Bay Area to proactively prepare for smoke this wildfire season
July 23, 2025
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7/17/2025 Air District and Alameda County District Attorney announce enforcement actions against Radius Recycling, formerly Schnitzer Steel
July 17, 2025
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7/14/2025 Air District lifts air quality advisory for wildfire smoke for Monday
July 14, 2025
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7/12/2025 Air District extends air quality advisory for wildfire smoke through Monday
July 12, 2025
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7/11/2025 Air District extends air quality advisory for wildfire smoke through Saturday
July 11, 2025
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7/10/2025 Air District issues air quality advisory for wildfire smoke for Thursday and Friday
July 10, 2025
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7/2/2025 Air District urges residents to skip the sparklers this Fourth of July
July 2, 2025
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6/23/2025 Air District extends air quality advisory for wildfire smoke through Monday
June 23, 2025
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6/22/2025 Air District issues air quality advisory for wildfire smoke for Sunday
June 22, 2025
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6/18/2025 Air District issues air quality advisory for smoke from Somersville brush fire for Wednesday evening
June 18, 2025
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6/12/2025 Air District increases Vehicle Buy Back Program incentive and expands eligibility effective July 1
June 12, 2025
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6/10/2025 Air District and Chevron reach settlement with enhanced requirements for air monitoring and transparency
June 10, 2025
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6/4/2025 Air District allocates $1.3 million to improve air quality in West Contra Costa County schools
June 4, 2025
Climate
Temperatures in and around the San Ramon and Diablo Valleys are warm in the summer and cool in the winter, largely because of their distance from the moderating effect of water bodies and because the California Coast Range blocks marine air flow into the valleys. The Carquinez Strait region remains temperate due to its proximity to water and oceanic air flows. In winter, average daily temperatures are mild, with tule fog common at night. Average summer temperatures are typically mild overnight and warm during the day, with cooler temperatures and stronger winds more common along the western coast. Wind speeds are generally low throughout the region and winds typically blow from northwest to southwest. However, strong afternoon gusts are common in the northern portion of the county around the Carquinez Strait. Annual rainfall averages between 18 and 23 inches across the county.
Interactive Air Monitoring Stations Map
Air Quality in Contra Costa 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.
Ozone and PM2.5 infrequently exceed health standards in the portion of Contra Costa County west of the East Bay hills. The San Francisco Bay keeps air temperatures above freezing in winter and well below 100 degrees on even the warmest summer days.
In eastern Contra Costa County, summer afternoon temperatures frequently approach triple digits, spurring ozone levels to exceed health standards. In winter, PM2.5 can be transported westward through the Carquinez Strait from the Central Valley where it adds to wood smoke, causing health standards to be exceeded.
Spare the Air Status
Last Updated: 4/21/2017