Dense fog is in the forecast Wednesday for parts of Los Angeles and Orange counties, but it will give way to record highs by Friday, forecasters said.
Foggy mornings will roll through the coastal areas until Friday when temperatures are expected to be 15 to 20 degrees above normal.
The heat wave is expected to last until Sunday when temperatures should start to drop, but will still be about 5 degrees above normal.
A marine layer will deepen over the weekend with coastal low clouds spreading into the valleys.
Temperatures in the Inland Empire and Palm Springs are expected to be between 98 and 104 by Thursday. There is a 69% chance of record-breaking heat in Palm Springs on Thursday and a 92% chance on Friday.