Rain, strong wind and even hail are in the forecast for parts of Los Angeles and Ventura counties through Friday, the National Weather Service warned.
A system that began to pull in cold, unstable air over San Luis Obispo and Santa Barbara counties will shift south toward Los Angeles by Thursday afternoon. Lightning and waterspouts are possible off the coast, the weather service said.
"It's very unseasonably cold for this time of year," said Stuart Seto, a specialist with the National Weather Service in Oxnard.
Temperatures will be in the low to mid-60s Thursday and Friday. At night, temperatures will drop to the upper 40s to mid-50s. The chance of rain on Thursday is 20% and will climb to 50% on Friday, Seto said.
Up to an inch of snow is forecast for the mountains at elevations as low as 5,000 feet.
The tumultuous weather could flare up minor debris and mud flows in areas recently scarred by wildfire.
Along the coast, meanwhile, forecasters are cautioning sailors to prepare for rough seas with thunderstorms and waterspouts.
A northwest swell is expected to bring high surf of up to 10 feet along the Central Coast Thursday morning. California’s beaches were pounded earlier this week with high surf from a huge southern swell that started in New Zealand.
But in the deserts, wind gusts as high as 50 mph could churn up dust and sand. Visibility will be reduced in the Antelope Valley and along Highways 14 and 138 due to strong crosswinds.