Strong Santa Ana winds are expected to intensify the wildfire threat in Southern California early this week and create a “particularly dangerous situation” in Ventura and Los Angeles counties, similar to circumstances in early November that helped fuel a significant wildfire, forecasters warned Monday.
Most southern parts of the state have received less than 0.25 inches of rain since Oct. 1 and the vegetation is dry and flammable. While wildfire risk plummeted in Northern California because of heavy rain in late November, Southern California largely dodged that storm.
Peak wildfire season is still in full swing in Southern California, and the risk will be especially great from Monday night into Tuesday. The area from Ventura County, to the north of Los Angeles, to San Diego County are expected to see sustained winds of 20-40 mph and isolated gusts up to 70 mph from the inland mountains to the coast. In the windiest locations, likely including Ventura and San Diego counties, isolated gusts could exceed 80 mph in the mountains.
Any new fire will spread rapidly under these conditions, Robbie Munroe, a meteorologist with the National Weather Service’s Los Angeles office, said Sunday. “The damaging winds will also likely lead to scattered downed trees, power lines and power outages,” he said.
Weather officials said the conditions are similar to those of early November, when dangerous winds belted Ventura County and fueled the Mountain fire, a nearly 20,000-acre inferno that damaged 243 structures, including homes.
The weather service issued a series of red flag warnings then, and in portions of Ventura and Los Angeles counties, the warning carried the rare designation of a “particularly dangerous situation.” This week’s warning for these counties uses the same strong message.
Munroe said the label was created with the idea that these extreme events would occur every three to five years. “As we’re seeing within about a month or so of the last one, it can happen twice in the same year,” he said. “And that, in fact, happened back in 2020 as well.”
Northern California, the Central Valley and the Sierra Nevada are not expected to see strong winds in this event, he said.
The strongest winds are expected Tuesday.
Strong winds and bone-dry air and vegetation are the perfect recipe for rapid wildfire spread, and the weather service’s Los Angeles office issued red flag warnings from Monday into Wednesday for large portions of Ventura and Los Angeles counties. “That’s going to include all the mountains,” said Rose Schoenfeld, a meteorologist with the weather service’s Los Angeles office.
Malibu, in particular, often gets raked by winds in Santa Ana events, and Matt Shameson, a meteorologist with the U.S. Forest Service, said Tuesday sustained winds of 25-30 mph with isolated gusts of about 55 mph are possible. The Broad fire broke out there during the early-November windstorm.
The weather service’s San Diego office also issued a Monday-to-Wednesday red flag warning for a large portion of San Diego, Riverside and San Bernardino counties, including the Inland Empire.
Santa Anas are offshore winds that blow from the north, northeast or east into Southern California, pushing dry air from inland valleys toward the coast, fanning vegetation and turning it into tinder. The winds entered the forecast this week when a low-pressure system moved down from British Columbia into the Pacific Northwest and Nevada. When the system reaches the Four Corners region Monday night into Tuesday morning, it will propel dry air into Southern California, pushing down humidity levels and acting like a giant leaf blower. That is when conditions will begin to become especially dangerous.
The winds are expected to develop Monday, intensify overnight, peak Tuesday and gradually weaken into Wednesday.
“The period with the strongest winds will run from about 10 p.m. Monday to 2 p.m. Tuesday,” said Shameson, a meteorologist with the U.S. Forest Service.
Shameson is particularly concerned about fires developing in the greater San Diego area Tuesday. “San Diego hasn’t seen much fire activity for a while,” he said. “I think they’re due for some.”
Humidity levels are predicted to plummet with the driest areas in the teens to single digits, while temperatures are generally expected to be normal at the height of the event Tuesday.
On Wednesday, the winds are expected to be calmer but the air will likely be extremely dry. “Relative humidity values will be between 5 and 12% in the mountains into Wednesday,” said Casey Oswalt, a weather service meteorologist in San Diego.
This article originally appeared in The New York Times.
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