The wildfire in San Clemente, located about an hour south-east of Los Angeles, was fuelled by dry, warm and gusty north-east winds known as Santa Anas, which blow from the interior of southern California toward the coast. The National Weather Service said winds of 32 to 56 km/h were expected on Friday, with gusts reaching 80 to 112 km/h in some areas. The strongest winds were forecast through Friday afternoon.
A separate blaze in Malibu, a coastal suburb of Los Angeles, prompted evacuation orders and warnings for a large swath of the Santa Monica Mountains. A large cloud of black smoke over the hilltops could be seen on nearby cameras and from kilometres away.
The fires have led to evacuations and tens of thousands of residents without power after utilities shut off electricity to reduce the risk of additional fires. Emergency crews were working to save structures in San Clemente, where thick smoke obscured the sun.