The warning, which started at 5 a.m. Tuesday, was expected to stay in effect until 8 p.m. Wednesday. Wind and heat advisories were also issued.
Strong Santa Ana winds, high temperatures and low-humidity create extreme fire danger.
Temperatures were expected to climb to record or near-record highs, with the Valley and Inland Empire facing triple-digits. Los Angeles and Orange counties and High Desert communities are expected to reach the high-90s.
Parking restrictions will be in effect in Los Angeles and Pasadena to keep narrow hilly streets clear.
Extra lifeguards were called in to Manhattan Beach to deal with the larger crowds.
On Tuesday, a fire fueled by windy and dry conditions in the San Diego area spread over 700 acres. About 20,000 people were temporarily evacuated. It was 5 percent contained on Wednesday.
Like ABC7Weather on Facebook to stay on top of the latest weather conditions.CNS contributed to this report.
