The most damaging fire was in Ventura County northwest of Los Angeles, where 150 structures were confirmed destroyed. But a fire official said he suspected "hundreds more" would be lost when flames died down enough to make a thorough assessment.
In the San Gabriel Mountains foothills of Los Angeles about 45 miles (72 kilometres) away from the city, 30 structures burned.
Mayor Eric Garcetti said the gusty winds expected to last most of the week had created a dangerous situation and he urged 150,000 people under mandatory evacuation orders to leave their homes before it's too late.
The fires in Ventura County lit up hillsides and spread rapidly Monday evening from rural rolling hills to dense subdivisions.
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Residents, already warned of extreme fire danger, were sent automated phone alerts and evacuations appeared to proceed smoothly.
As the sun rose yesterday, the first of at least three additional Southern California fires broke out, fuelled by stiff winds that prevented firefighting aircraft most of the day from dumping water to protect homes or attack the march of flames.
In addition to prompting hasty evacuations, the fires shut down two freeways for hours and sent heavy, acrid smoke billowing over the Los Angeles area, creating a health hazard for millions.
The Ventura wildfire exploded to nearly 80 square miles (207 square kilometres) in a matter of hours. It was fanned by dry Santa Ana winds clocked at well over 60 mph (96 kph) and spit embers up to a half-mile (0.8 kilometres) ahead of fire lines.
Lisa Kermode ignored the first evacuation alert that buzzed on her phone when it said the fire was 15 miles (24 kilometres) away from her home. But the flames were nearly on top of her an hour later when she rounded up her three children, still in their pajamas, and told them to grab some jeans so they could leave.
"We got knots in our stomach coming back up here," Kermode said. "We lost everything, everything, all our clothes, anything that was important to us. All our family heirlooms, it's not sort of gone, it's completely gone."
The fires came just eight weeks after the deadliest and most destructive series of wildfires in state history burned through Northern California and its fabled wine country and killed 44 people dead and destroyed 8,900 homes and other buildings.
Fires are not typical in Southern California this time of year but can break out when dry vegetation and too little rain combine with the Santa Ana winds. Hardly any measurable rain has fallen in the region over the past six months.
Fires in those settings are likely to become more frequent as climate change makes fire season a year-round threat and will put greater pressure on local budgets, said Char Miller, a professor of environmental analysis at Pomona College who has written extensively about wildfires.
"There are going to be far greater numbers that are going to be evacuated, as we're seeing now," Miller said. "These fires are not just fast and furious, but they're really expensive to fight."
Some 3,000 homes remained under threat in Ventura County, said Todd Derum of the California Department of Forestry and Fire Protection. Officials expect a better assessment of damage today, but suspect "hundreds more" homes were lost, Derum said.
Aerial footage showed dozens of homes in one neighbourhood burned to the ground and a large subdivision in jeopardy as embers blew about wildly. Burned-out cars sat on their wheel rims next to destroyed homes.
More than 27,000 people were evacuated, and one firefighter suffered bumps and bruises in a vehicle accident in Ventura County.
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