What started the wildfires raging across the Los Angeles area?

Fire officials are investigating the causes of multiple wildfires that are destroying homes and forcing thousands to evacuate across parts of Southern California on Wednesday.

The Palisades Fire started burning around 10:30 a.m. Tuesday and has scorched thousands acres around the beach towns of Santa Monica and Malibu. Around 6:30 p.m., the Eaton Fire broke out in Altadena near Pasadena and swelled to more than 10,000 acres. By 10:30 p.m. a smaller blaze named the Hurst Fire had ignited in Sylmar, in the San Fernando Valley northwest of downtown Los Angeles and consumed about 500 acres.

The cause of all three blazes are still under investigation, according to Cal Fire. But the powerful Santa Ana winds are likely driving their rapid growth.

"The combination of low humidity, dry fuels and shifting winds has heightened the potential for spot fires and rapid expansion," Cal Fire said in an update.

How do wildfires start? The natural and artificial causes of wildfires explained.

Even before the fires started, the National Weather Service had issued its highest alert for extreme fire conditions for much of Los Angeles County. The weather service office in Los Angeles warned Monday that wind gusts could reach 100 mph in some areas this week, prompting "extreme fire behavior" wherever blazes ignited.

"This is a particularly dangerous situation ? in other words, this is about as bad as it gets in terms of fire weather," the weather service office in Los Angeles warned Monday. "Stay aware of your surroundings. Be ready to evacuate, especially if in a high fire risk area. Be careful with fire sources."

What causes wildfires?

A wildfire, an uncontrolled blaze that occurs on open land with vegetation, can be ignited by natural or artificial causes.

Lightning is the most common natural cause of wildfires. In higher elevations lightning sometimes strikes dry vegetation, which sparks a fire that can easily become uncontrollable, particularly when fueled by dry winds.

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In cities with roads near wildlife, such as in Southern California, it is very common for vehicles to unknowingly ignite a fire, Luca Carmignani, a Fire Advisor from the University of California Agriculture and Natural Resources, previously told USA TODAY.

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'We can expect to see larger wildfires': Climate change helping drive an increase in large wildfires in the US

“For example, you have a truck with a train that drags on the road and generates sparks,” Carmignani said. “Or you have like a catalytic converter, there are different ways that cars and trucks can start a fire from the road.”

Strong winds can cause power lines to move, which may generate sparks that eventually land on dry fuel such as grass or vegetation, Carmignani said. He added that unextinguished campfires are also a prevalent human cause of wildfires.

Is it wildfire season?

Historically, wildfire season typically begins in July and ends around late November to early December, Carmignani said. This time of year has the driest conditions which are perfect for igniting and burning vegetation.

Last month, the Franklin Fire in scenic Malibu was quickly contained while November’s Mountain Fire burned tens of thousands of acres, destroyed and damaged hundreds of homes in western Ventura County and was the third most destructive wildfire in Southern California since at least 2013, according to the National Weather Service.

The National Weather Service's Los Angeles office issued a red flag alert Tuesday, the first in January since 2021, according to the Los Angeles Times.

"November, December, now January ? there’s no fire season, it’s fire year. It’s year-round," California Gov. Gavin Newsom said at a press conference.

Climate change causing concern

"Climate change is leading to larger and more severe wildfires in the western United States," the 2023 National Climate Assessment reported. Warmer temperatures create conditions that make fire behaviors more dangerous, the assessment found.

Jon Keeley, a senior research scientist with the U.S. Geological Survey, previously told USA TODAY climate change isn’t the only reason for the increase in large fires.

In California, population growth, increasing fire ignitions and the Santa Ana winds are bigger factors in wildfires, Keeley said. These factors don’t appear to be affected by climate change right now, and climate change is likely to be a bigger driver in the northern part of the state rather than the south, he said.

Contributing: John Bacon and Dinah Voyles Pulver, USA TODAY

(This story was updated to add new information.)

This article originally appeared on USA TODAY: How did the California wildfires near Los Angeles start?