Dry weather and merciless winds, with gusts predicted to reach the strength of a Category 1 hurricane in mountainous areas, threaten to intensify the already devastating Southern California wildfires that have driven 110,000 people from their homes.
Photos: Santa Paula, California fire rages
Thousands of firefighters -- 2,500 on the massive Thomas Fire alone -- have been working nonstop to battle the blazes racing across hillsides and through neighborhoods, officials said. Almost 9,000 homes are without power. Officials have shut down hundreds of schools spanning at least 15 districts.
Despite a brief respite in the winds Wednesday, they began picking up again in the evening. A gust of 85 mph was detected in Ventura County. Forecasters say Thursday will bring gusts of 80 mph in the higher altitudes, while winds of 50 to 70 mph will make firefighters' mission extremely difficult in Ventura and Los Angeles counties.
The humidity won't help. It will still be low Thursday, meaning the trees and brush fueling the fires will continue to be tinder. Firefighters are exhausted and airborne embers are irritating their eyes.
"Honestly, the firefighters are taking a beating, but we have to acknowledge the residents because they're taking beating, too, but they're cooperating with our orders," said Thomas Kruschke, spokesman for the Ventura County Fire Department.
The battle to douse the blaze is especially arduous on the Santa Barbara-Ventura County line, where the terrain is steep and rugged, he said. Fire officials hope to get as many as a dozen helicopters in the air Thursday, but the winds have been playing havoc on the choppers and fixed-wing aircraft, Kruschke said.
The Thomas Fire was 5% contained as of early Thursday. At 96,000 acres, the fire is roughly the size of Denver.
Officials say they will see a "recipe for explosive fire growth" and an unprecedented fire danger score. According to the Los Angeles Fire Department, experts grade fire danger by measuring the moisture in dead vegetation, the temperature, wind speed and direction, and then assessing historical weather information.
A value of 48 is considered high danger, while 162 is extreme. Thursday's score: 296, a record.
It's not the only first that firefighters have experienced with the Southern California blazes. The scale used to measure the potency of the Santa Ana winds typically runs from gray, for little or no danger, to red, for high danger.
"The forecast for (Thursday) is purple," said Ken Pimlott, director at the California Department of Forestry and Fire Protection, or Cal Fire, according to CNN affiliate KCBS. "We've never used purple before."
Latest developments
• More evacuations: Several cities in the Ojai Valley are under mandatory evacuation. Satellite images by the National Weather Service showed the city of Ojai surrounded by fires.
• Areas of concern: Firefighters said they are keeping the Skirball Fire at bay but worry it will jump west of Interstate 405.
• School closures: More than 260 Los Angeles public and charter schools will be closed Thursday and Friday.
• Out-of-state help: About 300 engines are coming from fire departments in other states, Los Angeles County Fire Department Chief Daryl Osby said.
Stretching 140 square miles
The Thomas Fire in Ventura County, which sits just north and west of Los Angeles, grew significantly Wednesday to about 150 square miles. The Rye Fire in Santa Clarita is holding at 7,000, with 15% containment, while the Skirball Fire has burned about 475 acres and is 5% contained.
"There are still a few people still in their homes in the evacuation areas, and they should come out. There are still embers that can move and catch as we have wind conditions," Los Angeles City Councilman Paul Koretz said of the Skirball blaze.
Officials said they couldn't give a precise number of homes destroyed, because flames in burned neighborhoods were too intense. They estimated about 150 buildings had been destroyed as of Wednesday night. The number will increase once the focus shifts from firefighting and rescue to more damage assessment, fire officials said.
California Gov. Jerry Brown has declared an emergency for the county, freeing state resources such as the National Guard to support response efforts.
Freeway shutdown
The Skirball Fire near the tony Bel-Air area of Los Angeles startled commuters Wednesday morning on I-405.
The busy freeway was shut down over a 9-mile stretch for hours as the fire got closer.
"It was dark until I saw a gigantic ball of orange," motorist Tiffany Lynette Anderson wrote on Instagram, where she posted a picture of fire raging beside the highway before it was closed.
"I could feel the heat on my windows," said Los Angeleno Joy Newcomb, who also drove by the fire.
The freeway has since reopened, but some ramps remained closed.
Firefighters worked Wednesday night to keep the fire from jumping west of 405 and to battle some flare-ups, said Peter Sanders, a spokesman for the Los Angeles Fire Department.
Smoky hazards
Los Angeles authorities ordered parts of the Bel-Air district near the fire to leave, but those are just a fraction of the evacuations that have been ordered in Southern California since Monday night.
Smoke collected even in areas that weren't burning. Health officials warned people in the heavily populated San Fernando Valley and other parts of the northern Los Angeles area to limit their time outdoors.
A video posted to Instagram shows a Los Angeles County Fire helicopter maneuvering around heavy smoke to make a water drop on the Skirball Fire.
The smoke from the fires could be seen from the International Space Station. Astronaut Randy Bresnik wrote in one tweet: "I was asked this evening if we can see the SoCal fires from space. Yes Faith, unfortunately we can. May the Santa Ana's die down soon. #Californiawildfire."
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