The Bay Area Air Quality Management District is declaring today this year's sixth Spare the Air Day as the National Weather Service forecasts a high temperature of 97 degrees in Pleasanton and the Tri-Valley.
Tomorrow will be nearly as hot, with a high of 96 degrees forecast for mid-day Sunday.
These high early fall temperatures are expected to cause ozone pollution levels near the ground to reach unhealthy concentrations.
However, unlike previous days when smog alerts were issued through the Spare the Air program, there will be no free public transit and no ban on burning wood, the air district said in a statement.
Smog levels are expected to be particularly bad in the South Bay, according to air district spokeswoman Kristine Roselius, but residents throughout the Bay Area should make efforts to reduce their smog output.
"Smog is a regional pollutant," Roselius said.
She said people can make a difference by driving less, either by using carpools, taking public transportation or simply staying home.
Another way to help Saturday's impending poor air quality is to avoid doing weekend lawn work with machines that emit exhaust, Roselius said.
Not cooking outdoors on a barbeque would also help during the day of impacted air quality, Roselius said.
All residents - particularly those with respiratory conditions, elderly people and children - should either stay inside or reduce their time outdoors during the hottest part of the day to avoid having an adverse medical reaction to the heat and increased smog, Roselius said.
Long-term exposure to smog can reduce lung function, the air district said in a statement.
The National Weather Service reported that temperatures are expected to stay high throughout the Bay Area and the Monterey Bay region until Tuesday of next week.
The service said in a statement that the current high-pressure ridge passing through the region would cause "some of the warmest weather of the year."
Areas farther from the ocean or bays expected to reach the low 100s.
Conditions might heat up on Monday and Tuesday after the weekend, the weather service said. People who have plans outdoors are advised to make sure they always have ample amounts of water, sunscreen, and light-colored clothing.
Residents and visitors are also being reminded to never leave children or pets in the backseat of parked cars during particularly hot days.