The Air District has issued 3 Notices of Violation to Valero for violations of air quality regulations and/or permit conditions for the May 5 fire. This is an ongoing investigation, and more violations may be issued.
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Santa Clara County
Learn about Santa Clara County - its climate, potential air pollution concerns, and current air quality. You can also view upcoming Air District events in Santa Clara County and read about local efforts to improve air quality.
Latest News
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Air quality advisory for smoke from fire at ValeroMay 05, 2025
The Air District is issuing an air quality advisory for smoke in Southern Solano, northern Contra Costa, and northwestern Alameda counties, specifically communities between I-80 and I-680 bridges (Martinez, Pacheco, Concord and Port Chicago), but with some impact possible southward to Oakland, due to a fire at Valero.
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Spare the Air smog season beginsMay 05, 2025
The Air District is announcing the start of the Spare the Air summer smog season, which runs from May to October in the Bay Area.
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Air District Issues 18 Notices of Violation to Martinez Refining Company as a result of the February 1 fireMay 01, 2025
The Air District has issued 18 Notices of Violation to MRC for violations of air quality regulations and/or permit conditions for the February 1 fire. This is an ongoing investigation, and more violations may be issued.
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Upcoming Events
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Other News Articles
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4/7/2025 Air District to host virtual webinar overview of the proposed budget for Fiscal Year 2025-2026
April 7, 2025
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3/27/2025 Point Richmond and North Richmond Odor
March 27, 2025
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3/25/2025 Air District asks community members to help shape how millions in community funds are spent
March 25, 2025
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3/21/2025 Join Webinar to Explore Careers at the Air District
March 21, 2025
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3/13/2025 Air District’s Clean HEET Program now accepting applications
March 13, 2025
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3/5/2025 Air District launches Charge! Program, expanding Bay Area access to electric vehicle chargers
March 5, 2025
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3/3/2025 Notice Regarding Fraudulent Bay Area Commuter Benefits Program Letters
March 3, 2025
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2/13/2025 MRC Refinery Fire Information
February 13, 2025
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2/1/2025 Air quality advisory for smoke from fire at MRC Refinery in Martinez
February 1, 2025
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1/28/2025 Air District asks public not to light firecrackers and fireworks or burn wood over Lunar New Year holiday
January 28, 2025
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1/22/2025 Air District launches new name and branding
January 22, 2025
Santa Clara County is south of the San Francisco Bay, with San Mateo and Alameda counties bordering it to the north, Santa Cruz County to the west, San Benito County to the south, and Stanislaus and Merced counties to the east. Four Santa Clara County representatives sit on the Air District’s Board of Directors.
Climate
During the summer, mostly clear skies result in warm daytime temperatures and cool nights. Winter temperatures are mild, except for very cool but generally frost-less mornings.
Further inland where the moderating effect of the bay is not as strong, temperature extremes are greater. Wind patterns are influenced by local terrain, with a northwesterly sea breeze typically developing during the daytime. Winds are usually stronger in the spring and summer. Rainfall amounts are modest, ranging from 13 inches in the lowlands to 20 inches in the hills.
Interactive Air Monitoring Stations Map
Air Quality in Santa Clara 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.
Most of Santa Clara County is well south of the cooler waters of the San Francisco Bay and far from the cooler marine air which usually reaches across San Mateo County in summer. Ozone frequently forms on hot summer days when the prevailing seasonal northerly winds carry ozone precursors southward across the county, causing health standards to be exceeded.
Santa Clara County experiences many exceedances of the PM2.5 standard each winter. This is due to the high population density, wood smoke, industrial and freeway traffic, and poor wintertime air circulation caused by extensive hills to the east and west that block wind flow into the region.
Spare the Air Status
Last Updated: 4/21/2017