After a brief reprieve, Southern California is facing two days of dangerous winds that officials fear could expand current fires and spark new ones.

Firefighters on Monday established containment lines around the Eaton and Palisades fires and completed preparations ahead of the storm that is expected to hit swaths of the region, including Ventura County, the San Fernando Valley and parts of Los Angeles and the San Gabriel Valley, bringing gusts ranging from 45 mph to 70 mph.

Officials have made progress over the past few days as winds weakened, allowing air operations to prevent the Palisade Fire from hitting Brentwood and Encino. Authorities hope to be able to keep the plane flying Tuesday, but it's unclear how far conditions will allow.

"The situation is unclear at this time and we must not let our guard down," Los Angeles Fire Chief Christine Crowley said at a news conference Monday.

National Weather Service warnings of particularly hazardous conditions "are one of the loudest ways we can shout," said National Weather Service meteorologist Rose Schoenfeld.

"This is continued extreme fire weather and high wind conditions," Schoenfeld said.

The Palisades Fire has burned more than 23,700 acres and was 14% contained as of Monday. The Eaton Fire has burned more than 14,100 acres and is 33% contained, according to the California Department of Forestry and Fire Protection.

Mexican firefighters and emergency personnel have arrived in Los Angeles to help put out the blaze. Gov. Gavin Newsom said 72 firefighters arrived Saturday to join thousands of firefighters working the battle.

Another 1,000 California National Guard members were also sent to fire-ravaged Los Angeles. They will bring the total number of Guard members in the region to about 2,500, according to the governor's office.

Hundreds of federal personnel and aircraft have also been deployed to California to support firefighting efforts, President Biden said Monday.

About 92,000 people remain under evacuation orders, and another 89,000 live in areas where evacuation warnings have been issued.

Crowley said fire crews are well prepared for recent extreme weather events.

“As we speak, the City of Los Angeles Fire Department has maximized our resource capabilities and response capabilities. … I have strategically pre-positioned engine strike teams and task forces to work on firefighting in the city. Respond quickly to any new fires that break out,” Crowley said.

Preparations include strengthening fire lines around the Eaton and Palisades fires, clearing dry brush on surviving structures and mobilizing resources in areas where new fires could start. The Governor's Office of Emergency Services also prepositioned additional engines, fire crews, helicopters, bulldozers and water trucks across Southern California.

Crews are preparing for a worst-case scenario in which high winds prevent firefighting aircraft from strategically dropping retardant around the fire.

"The National Weather Service is predicting winds approaching hurricane force, so we are making emergency preparations," Los Angeles Mayor Karen Bass said. "My priority and the priority of others is to do everything we can to protect lives. ”

While the Eaton Fire District isn't expected to see wind gusts as severe as elsewhere in the county, firefighters are focusing on extinguishing surrounding hot spots to reduce the chance of wind picking up smoldering embers and carrying them into the fire. Los Angeles County Fire Department spokesman AJ Lester said.

He said winds on Tuesday and Wednesday are expected to be the most dangerous on the fire's northern end, where crews hope they can prevent the fire from spreading to the ridgeline.

"If that happens, the fire will spread down the hill from the other side and into other communities," including areas like La Canada Flintridge, Lester said. Similar efforts are underway at the Palisades Fire.

The confirmed death toll from the Palisade and Eaton fires jumped to 24 on Monday. Los Angeles County Sheriff Robert Luna said eight people died in the Palisade Fire and 17 people died in the Eaton Fire in Altadena.

Officials said 29 people, all adults, were still reported missing from the two fires.

Officials warned the death toll could continue to rise. Luna said the Eaton and Palisade fire districts are using cadaver dogs and grid searches for search and recovery operations.

"Unfortunately, we encounter the remains of community members every day," Luna said.

The Palisade and Eaton fires were among the deadliest in modern California history. The state's deadliest wildfire remains the Camp Fire, which leveled the Butte County town of Paradise in 2018 and killed 85 people. The next worst fires were the 1933 Griffith Park Fire, which killed 29 people; the 1991 Oakland-Berkeley Hills Fire, which killed 25 people; and the 2017 Tubbs Fire in Napa and Sonoma Counties. The fire killed 22 people.

Although there is no final count of the number of buildings destroyed, the fire is already one of the most destructive the state has ever experienced.

Damage assessments have identified 1,902 buildings destroyed in the Eaton fire, but inspection teams have only examined about 30 percent of the fire's footprint. Officials estimated that 7,000 structures were damaged or destroyed, including homes, businesses, small outbuildings and sheds, and even vehicles.

Officials estimate the Palisades Fire has destroyed more than 5,300 structures.

If those numbers hold up, the Palisade and Eaton fires would rank among the four most destructive wildfires in modern California history, according to Cal Fire.

Officials have been working to secure fire areas from those who allegedly traveled to the area to burglarize evacuated homes and commit other crimes. Authorities have arrested 34 people, including a burglary suspect who allegedly dressed as a firefighter.

Of those arrested, 30 were arrested in the Eaton Fire District and four were arrested in the Palisades Fire District, Luna said.

As officials try to determine the cause of the Eaton Fire, which has burned through Altadena and surrounding areas, investigators have focused on a transmission tower in Eaton Canyon. Early photos and videos taken by residents captured the first flames of the deadly Eaton Fire burning at the base of Southern California Edison transmission towers before rushing down canyons toward homes.

Edison officials have so far said they do not believe their electrical equipment is responsible. Four lawsuits were filed Monday against the utility.

Fire agencies are investigating whether downed Southern California Edison utility equipment may have played a role in starting the 800-acre Hurst Fire near Sylmar, company officials said. The fire, which started Jan. 7 near Diamond Road in Sylmar, was 95% contained as of Monday and evacuation orders have been lifted, but firefighting efforts are continuing.

The utility reported Friday that a downed conductor was found at a tower near the fire, but "it is unknown whether the damage observed occurred before or after the fire."

Authorities are still trying to determine the cause of the Palisades fire, but officials who spoke on condition of anonymity told The Times it appeared to be human in origin. In recent days, attention has been focused on a popular Temescal Ridge trail where an earlier fire broke out.

While this week's fire weather is not expected to be as severe as last week's historic storms that fueled the Palisade and Eaton fires, weather officials warn it could lead to extreme fire behavior that could turn small blazes into raging blazes Fire.

This wind event will be a more traditional Santa Ana wind, with winds blowing from the east and spreading fire westward. Last week's storms were made worse by "mountain wave winds," which are gusty winds that blow quickly down hillsides and then become stronger as they hit flat areas. The phenomenon triggered brief bursts of strong and dangerous winds, with gusts of up to 100 mph reported near Altadena. Schoenfeld said last week's winds were mostly coming from the north and affected areas that don't typically see strong winds during Santa Ana events.

Areas covered by special hazard warnings affect relatively small areas, primarily the northern San Fernando Valley, including Porter Ranch and San Fernando; the western Santa Monica Mountains and Malibu areas; and large swaths of Ventura County, including Ventura, Simi Valley and Fillmore; and the Grapevine section of Interstate 5.

Southern California hasn't received much rain this winter, fueling concerns before winds pick up. Since Oct. 1, downtown Los Angeles has received just 0.16 inches of rain, which is basically nothing compared to the average rainfall of 5.23 inches for this time of the water year.

Schoenfeld said the risk of downed trees and power lines is higher than with a typical red flag fire weather alert. In particularly hazardous areas, public safety power is more likely to be shut off.

The Los Angeles Department of Water and Power said Monday that about 17,600 customers were without power in high-fire risk areas including Pacific Palisades, Brentwood, Sylmar and Encino.

More than 25,000 Edison customers in Los Angeles County were without power Monday afternoon, and another 122,000 customers in the county may be without power in the coming days, according to the utility.

This is the fourth warning of particularly hazardous conditions since the fall. Each of the three previous warnings was followed by major, destructive fires — the 19,904-acre Wildfire in Ventura County, which burned more than 240 structures in November; the 4,037-acre Franklin Fire in December; Malibu spread quickly, destroying 20 buildings; and last week's Palisades and Eaton fires.

Traditional red flag warnings, warnings of severe fire weather conditions, have been in effect across large swaths of Southern California since Saturday and will remain in effect through Wednesday night. Red flag warnings cover a much wider area than particularly dangerous situations.

"The next few days will be critical for us to extinguish existing fires and prevent any new fires," Los Angeles County Supervisor Kathryn Barger said. "Thank you for taking this seriously."

New York Times staff writers Rebecca Ellis, Clara Hart, Salvador Hernandez, Faith Pinho, Jenny Jarvey, Laura J. Nelson, Kay Vin Rector, Ruben Vives and Julia Wick contributed to this report.