A strong Santa Ana wind event will hit Ventura, Los Angeles and Orange counties and is expected to remain strong until a high wind warning ends at about 2 p.m. Saturday, the agency said.
The high wind warning means wind in the area is expected to blow at 20-30 mph, with gusts up to 50 mph.
The winds could be damaging in many areas, but the strongest are expected in the mountains, including the Santa Monica Mountains, where damaging peak gusts to 80 mph are expected.
A car crashed into a tree that was blown over onto the 101 Freeway in Studio City, causing a major traffic jam at about 2:15 p.m.
Dust and debris kicked up in Rancho Cucamonga, an area known for strong breezy conditions.
"When the winds come, we have to batten down because sometimes things can blow over the 210," said Rancho Cucamonga resident Regina Brust.
In Fontana, just the next city over, an overturned FedEx truck was blocking the 10 Freeway at the Sierra Avenue off ramp. Officials said the heavy wind conditions pushed the truck to its side, but the driver was left unharmed.
In Santa Ana and other Orange County cities, cars were left mangled from toppled trees that were too weak to endure the winds.
A red flag warning denoting fire-weather conditions will also be in effect from noon Friday to 6 p.m Saturday. The strong Santa Ana winds with a mix of low humidity and very dry vegetation have prompted the warning in mountain, forest and valley areas, specifically the Santa Monica Mountains, inland Orange County, and the San Fernando, Santa Clarita and eastern San Gabriel valleys and the L.A. County coastal zone.
The National Weather Service warns that strong winds can cause downed trees, power outages and dangerous driving conditions.
City News Service contributed to this report.