A cold Canadian air mass moving into Southern California could drop temperatures across inland valleys into the 30s and 20s beginning Tuesday night and is expected to last through the rest of the week.
The coldest weather is expected Wednesday night through Friday morning.
Widespread frost is possible across the Santa Barbara coast and into Ojai Valley in Ventura County and the Antelope Valley in Los Angeles County, according to the National Weather Service.
The agency issued a freeze watch across areas from San Luis Obispo County to Los Angeles County. Weather service officials urged residents to protect pets and livestock by keeping them indoors and to cover crops and sensitive plants.
The below-normal temperatures are to be caused by low pressure generated in Canada.
The weather system is expected to generate gale-force winds around 40 knots in coastal waters and gusty northwest winds along the 5 Freeway corridor in the Antelope Valley, according to forecasters.
On Monday night, temperatures ranged from the 40s to the 60s in Southern California. It was 59 degrees in downtown Los Angeles, 63 in Burbank, 54 in Los Alamitos and 41 at Big Bear Airport, according to the weather service.