The Air District is extending a Spare the Air Alert through Saturday, September 23, due to continued wildfire smoke impacts across the region.
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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.
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September 22, 2023
Air District extends Spare the Air Alert through Saturday
The Air District is extending a Spare the Air Alert through Saturday, September 23, due to continued wildfire smoke impacts across the region.
Sep
2
1
September 21, 2023
Air District extends Spare the Air Alert through Friday
The Air District is extending a Spare the Air Alert through Friday, September 22, due to continued wildfire smoke impacts across the region.
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September 20, 2023
Air District issues Spare the Air Alert through Thursday
The Air District is issuing a Spare the Air Alert due to wildfire smoke for Wednesday, September 20 through Thursday, September 21, which bans burning wood, manufactured fire logs or any other solid fuel, both indoors and outdoors.
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9
September 19, 2023
Air District issues air quality advisory through Wednesday
The Air District is issuing an air quality advisory for wildfire smoke through Wednesday, September 20. Smoke from fires in Northern California and Oregon is expected to impact air quality throughout the Bay Area area, causing air quality to reach high-moderate on the U.S. EPA’s Air Quality Index. Smoky, hazy skies may be visible and the smell of smoke is possible. Pollutant levels are NOT expected to exceed the national 24-hour health standard and there is no Spare the Air Alert in effect.
September 7, 2023
September 6, 2023
August 30, 2023
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.
Contra Costa County’s climate is also affected by regional Bay Area climate influences.
Interactive Air Monitoring Stations Map
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.
Last Updated: 2/14/2019