The cooldown comes as a high-pressure system weakens and onshore flow increases, while little change is expected across interior areas.
A noticeable cooling trend is expected Friday and Saturday as onshore flow increases, the marine layer begins to return, and high pressure continues to weaken, forecasters said.
By Sunday, a more tranquil weather pattern is expected to settle over Southern California, with temperatures in most areas about 5 to 10 degrees below seasonal averages through Wednesday.
The heat came as Southern California continued recovering from high surf and coastal flooding generated by Hurricane Marie, which damaged beachfront properties in Long Beach, Dana Point and Malibu earlier this week.
City News Service contributed to this report.