A heat advisory that the National Weather Service issued remains in effect until 8 p.m. Thursday as temperatures climb to the 90s and 100s in parts of the Bay Area.
Temperatures across the interior of the region will range from 95 to 107 degrees, according to weather officials.
The heat advisory applies to North Bay and East Bay mountains and valleys, interior Monterey County, southern Salinas Valley, Santa Clara Valley and inland cities.
Air quality will be poor as a result of the high temperatures, according to the Bay Area Air Quality Management District, which has issued a Spare the Air alert for Thursday.
Spare the Air alerts are issued when ozone pollution is forecast to reach unhealthy levels. Excessive amounts of smog, or ozone, can cause throat irritation, congestion and other medical problems, particularly for seniors, children and those with respiratory and heart conditions, according to the air district.
The district is encouraging Bay Area residents to do their part by finding alternatives to driving alone, such as carpooling or taking public transit.
To find out when a Spare the Air alert has been issued, people can sign up for email alerts at sparetheair.org; call 800-HELP-AIR (4357-247); download the Spare the Air smartphone app for iPhone or Android devices; or connect with Spare the Air on Facebook, Twitter or YouTube.