Boy swept away in California storms

Rescuers have ended the search for a five-year-old boy who was swept away by floodwaters in central California while the entire community of Montecito was ordered evacuated as residents grappled with flooding and mudslides as the latest in a series of powerful storms walloped the state.

Tens of thousands of people remained without power and some schools closed for the day. The number of deaths related to the storms climbed from 12 to 14 on Monday, state officials said.

The search for the boy was called off at 3pm because the current and rising water levels of the Salinas River were too dangerous for divers, the San Luis Obispo County Sheriff's Office said.

The boy's mother was driving a truck when it became stranded in floodwaters just before 8am near Paso Robles.

Bystanders were able to pull the mother out of the vehicle but the boy was swept downstream.

Meanwhile, south of Paso Robles, the entire community of Montecito were under an evacuation order that came on the fifth anniversary of a mudslide that killed 23 people and destroyed more than 100 homes in the coastal enclave.

The National Weather Service reported that at least 20 centimetres of rain fell over 12 hours, with more predicted.

Upscale Montecito is squeezed between mountains and the Pacific and is home to celebrities including Oprah Winfrey, Rob Lowe and Harry and Meghan, the Duke and Duchess of Sussex.

Santa Barbara County Sheriff Bill Brown said the decision to evacuate nearly 10,000 people was "based on the continuing high rate of rainfall with no indication that that is going to change before nightfall".

Up the coast, evacuation orders were issued in Santa Cruz County for about 32,000 residents living near rain-swollen rivers and creeks.

A large, muddy slide blocked both lanes of southbound Highway 17, a key but windy route into Santa Cruz from the San Francisco Bay Area.

In northern California, several districts closed schools while the California Highway Patrol shared video of large boulders skidding down hillsides to block state roads.

More than 35,000 customers remained without power in Sacramento, down from more than 350,000 a day earlier after gusts of 97km/h knocked trees into power lines.

President Joe Biden issued an emergency declaration Monday to support storm response and relief efforts in more than a dozen counties, including Sacramento, Santa Cruz and Los Angeles.