SACRAMENTO — The coast redwood crashed through the roof and into Nicole Valentine’s bedroom while she was away at a party, trying to ignore the powerful storms that were hammering Northern California with fierce winds and rain. On the phone, her neighbor was almost incoherent.
“She’s like, ‘A tree just fell on your house! I smell gas! I called 911!’” Ms. Valentine, a mother of two and a lawyer in Sacramento, said. “I said, ‘Wait — what?’ Thank goodness no one was at home but our labradoodle, Charlie. My husband ran home immediately.”
In the days since that call on New Year’s Eve, cumulative storms have pummeled California — and Ms. Valentine and her family have huddled in an Airbnb with Charlie, who survived unharmed. As they have tried to schedule insurance adjusters, versions of their terrifying experience have proliferated across the nation’s most populous state.
Stressed by drought, whipped by wind and weakened at the roots by relentless rain and flooding, trees — tall and short, ancient and young, in mountain preserves and suburban yards — have toppled across California this week in breathtaking numbers, the most visible sign of a state veering between environmental extremes.
A procession of atmospheric rivers has interrupted an epic drought responsible for the driest three years on California record. The sudden swing from scarcity to excess with back-to-back storms is testing the state’s infrastructure broadly, straining the power grid, levees, drainage systems and roads from the Pacific Coast to the Sierra Nevada.
On Thursday, the pressure mounted as rain swelled rivers and snowy whiteouts obscured mountain passes. In San Francisco, trains were delayed amid systemwide disruptions on the Bay Area Rapid Transit. In Santa Cruz County, a tidal surge carried off parts of piers and forced the City of Santa Cruz to close its wharf as a safety measure. In Southern California, huge waves threatened lifeguard towers in Los Angeles County and flooded the Pacific Coast Highway in Huntington Beach, as the rain moved southward.
By Friday morning, tens of thousands of customers, mostly in Northern California, were still without power as communities prepared for yet another round of drenching rain. Forecasters with the National Weather Service in the Bay Area said the next atmospheric river was expected to arrive late Friday and spread south to Central California on Saturday, raising the risk of more flooding and mudslides across the northern section of the state. Farther inland and around the Sacramento area, conditions were expected to be equally dangerous.
If the storm had a theme, it was in the uprooted and broken trees that seemed to blanket the rain-soaked landscape — a loss and a hazard that the director of the state water resources department, Karla Nemeth, had warned would be “the signature of this particular event.”
Falling trees slammed into power lines on the Central Coast, shut down Highway 101 in Humboldt County and snarled rail service in Burlingame and San Francisco. They injured a California Highway Patrol officer at a crash scene in San Jose and ensnared cars on rain-soaked roads in Marin County. On Wednesday, fire officials said, a redwood in the Sonoma County community of Occidental crashed into a mobile home, killing a toddler.
In the Fruitvale neighborhood of Oakland, a tree crashed through a public housing apartment on Wednesday, where Victoria James lives with her adult daughter, her two younger children and her 3-year-old granddaughter. “Everything shook and went black,” Ms. James said. “I thought it was an earthquake.”
When she saw branches poking through her ceiling and more limbs falling, she said, she grabbed the children and started running.
“There were live wires everywhere,” she said. “My neighbors had to direct us because it was pitch black out. We just left with what we had on our backs. Literally ran out — one kid didn’t even have on tennis shoes.”
In Sacramento, which bills itself as the “City of Trees,” the atmospheric rivers claimed nearly 1,000 trees in six days, according to the city’s urban forester, Kevin Hocker, who called the toll “much more than we’ve seen in other storms.” He estimated that 60 fell in one city park alone.
On the State Capitol grounds, a giant sequoia lay uprooted on Thursday, felled by the storms and surrounded with hazard tape and scattered drifts of branches; its fall sheared the limbs off one side of a nearby Torrey pine. Paula Peper, a retired U.S. Forest Service urban ecologist in Sacramento, estimated that the giant sequoia had stood for 80 to 100 years, through as many as 18 governors.
At Sacramento City College, a downed cedar, huge and fragrant, blocked the entrance to campus. In a manicured neighborhood near the American River, Marco Leyva, a local landscaper, scrambled to retrieve fallen tree limbs, his truck piled high with redwood, oak and liquid amber. Some, he said, appeared to have fallen partway in the New Year’s Eve storm, “and then the wind this time just knocked them down.”
In a news conference, Ms. Nemeth, the state water resources director, blamed the horticultural devastation on the drought as well as the violent weather. “We’re moving from extreme drought to extreme flood,” she said. “What that means is, a lot of our trees are stressed.”
At the same time, weather systems shifted by climate change have amplified wind and precipitation, said Jeffrey Mount, a senior fellow at the Public Policy Institute of California’s Water Policy Center. Last weekend’s storm was very wet — essentially, an atmospheric fire hose hanging over California — but this week’s “bomb cyclone” storm brought much more wind, Dr. Mount said.
The one-two punch of ever more saturated soil and speeding winds, scientists say, has made it tougher for trees to stay upright.
“It is not a surprise when we start getting these 50- to 70-mile-per-hour gusts that these big, old trees that are stressed and have their feet planted in what is essentially mud at this point — they fall over,” Dr. Mount said. “An astonishing number of these big trees go toes up in these big storms.”
Emily Griswold, director of horticulture and teaching gardens at the University of California, Davis Arboretum, said that the swings between climate extremes have left even healthy trees more vulnerable. On New Year’s Eve, some 15 thriving trees at the arboretum uprooted — including a “beautiful, healthy” Guadalupe Island cypress planted in 1936.
She and her colleagues research which trees and plants would be best to help shade cities and which would be able to thrive in a rapidly changing California.
Much of their research so far has focused on extreme heat and drought. But the recent storms have shown that those inquiries must expand, she said.
“It’s like heat, drought, flood — hell or high water,” Ms. Griswold said. “We’re definitely looking closely at what fails, why did it fail, what can we learn from this, and how can we plant more wisely in the future?”
Brian Ferguson, a spokesman for the California Governor’s Office of Emergency Services, said the thousands of downed trees have been among the biggest challenges the state has encountered in managing public safety in this storm system. Falling trees not only threaten buildings and power lines, he said, but also can damage levees by toppling near waterways where branches and debris can be propelled downstream.
The new climate reality, he said, has meant that disasters intertwine and compound one another: Drought worsens and lengthens fire seasons. Global warming intensifies heat waves. Precipitation that can no longer fall as snow lands as a deluge, and flora and fauna strain to survive the ecological disruption.
The current disasters, and the living things that endure them, Mr. Ferguson said, underscore the reality that “we are one planet.”
“I’m not a scientist, just a dad with two eyes and a brain, but it’s so clear that the world is changing around us,” he said.
Holly Secon and Derrick Bryson Taylor contributed reporting.