A Spare the Air alert has been extended through Sunday due to rising levels of vehicle smog amid high temperatures and lack of wind across the Bay Area.
The Bay Area Air Quality Management District, which was initially issued for Saturday only, recommends people use their vehicles only when absolutely necessary and only exercise during the early morning hours.
Smoke from wildfires in Central and Southern California also is expected to drift into the region, making the air that much worse, the air district said.
High temperatures are expected to reach into the upper 80s to mid-90s in most inland areas, weather forecasters say.
For more information about air quality and Spare the Air alerts, visit the air district's website.