The latest Pacific storm unleashed torrential downpours and damaging winds in California on Tuesday, a day after heightened flood and mudslide risks prompted thousands of evacuations and caused widespread power outages.

More than 33 million Californians were threatened by severe weather throughout the day as “heavy to excessive” rainfall was expected across the state, especially in southern California, as winds gusts were clocked at more than 64km an hour in many places, the National Weather Service (NWS) said.

The high winds wreaked havoc on the power grid, knocking out electricity to tens of thousands of Californians.

As many as 220,000 homes and businesses were without electricity on Tuesday morning, according to data from Poweroutage.us.

The treacherous weather, expected to dump as much as 18cm of rain in some parts by Wednesday, could produce widespread flooding, rapid water rises, mudslides and landslides, especially in areas where the ground has been saturated from previous heavy rainfall, the service warned.

The 4,000 residents in Planada, a community in Central California, started their Tuesday morning with an order to evacuate their homes by the county sheriff’s office.

“At this time our deputies are going to door to door to help residents evacuate,” the office said on Twitter, urging residents to head to the town’s Dollar General store where buses were ready to take them to a shelter.

Experts say the growing frequency and intensity of such storms, interspersed with extreme dry spells, are symptoms of climate change, posing greater challenges to managing California’s precious water supplies while minimising risks of floods, mudslides and wildfires.

The weather service’s forecast comes after the evacuation of some 25,000 people, including the entire picturesque town of Montecito, an affluent coastal enclave 90 miles northwest of Los Angeles, and nearby areas of the Santa Barbara coast.

The Montecito evacuation zone was among 17 California regions where authorities worry the ongoing torrential downpours could unleash lethal cascades of mud in hillsides that past wildfires stripped bare of vegetation.