• Firestorms in Los Angeles have burned over 5,000 acres, destroying homes and killing two people.
• One of the two biggest blazes, the Palisades Fire, could be the costliest in US history.
• The fires have spread so fast in part because of a windstorm and flood-drought whiplash.

All was well in Los Angeles at around 10 a.m. on Tuesday.

Less than 24 hours later, 2,925 acres of the Pacific Palisades were ablaze in what is being called the worst wildfire in Southern California since 2011.

Three more blazes have ignited in the area, with one, the Eaton Fire, engulfing another 2,000-plus acres.

Firefighters had not contained the blazes as of Wednesday morning, the Los Angeles Fire Department said.

More than 1,000 structures have burned, at least two people have died, and the fires could get even worse in the coming hours.

California is no stranger to fires, but this situation is different and especially dangerous for a few reasons.

An 'urban firestorm' that could be the costliest in history

Few brush fires in California history have intruded into such vast areas of dense, urban housing.

The UCLA climate scientist Daniel Swain called it an "urban firestorm" as he assessed live images of the developing Eaton Fire on Tuesday morning.

Perhaps the best historical comparison is the 1991 Tunnel Fire, which raged through more than 1,500 acres of Oakland, but it was smaller than either of the two giant blazes in Los Angeles. It killed 25 people and injured 150, and ranks as the third-deadliest and third-most-destructive fire in California history.

The true toll of this week's fires won't be clear until later.

Swain said that he and several colleagues have estimated that the Palisades Fire could be the costliest on record in the US because of the number of structures burning and the fact that those homes are some of the most expensive in the world.

"We are looking at what is, I think, likely to become the costliest wildfire disaster in California, if not national history, along with a number of other superlatives," Swain said.

A historic windstorm spread the fire fast

A powerful windstorm buffeted the flames throughout Tuesday and into Wednesday morning, with gusts of wind reaching up to 90 miles an hour, according to the National Weather Service.

During a 2 ½ hour period overnight, the Palisades Fire's size more than doubled, per the fire service's reports.

The winds were so powerful on Tuesday evening that water- and retardant-dropping aircraft could not fly.

It's a phenomenon that scientists have warned about: a deadly combination of high winds and dry, open land — such as the brushland now being swept by flames in Los Angeles — amounting to fires that move faster than emergency responders can keep up with.

"It's certainly unusual how fast it's grown," Douglas Kelley, a researcher at the UK's Centre for Ecology and Hydrology, told Business Insider. "It's definitely a lot faster than I guess a lot of people were expecting in the area at the time."

A study published in Science in October found that while only about 3% of US fires over a nearly two-decade period could be considered "fast fires," they caused disproportionate damage.

"The most destructive and deadly wildfires in US history were also fast," wrote the study's authors, led by University of Colorado Boulder's Jennifer Balch.

Between 2001 and 2020, fast fires accounted for 78% of fire-destroyed buildings and a full 61% of suppression costs — or $18.9 billion, the scientists wrote. And they are getting more frequent, the study said.

The windstorm was bad luck. But the other primary factor in the fires' rapid explosions — the fuel — is strongly linked to the climate crisis.

Weather whiplash made abundant fire fuel

Southern California has experienced heavy rainfall and flooding the past two winters — which is a huge part of the problem.

Abundant rainfall spurred an explosion of grasses and brush, the primary fire fuel in Southern California. Then, with very little rainfall in the past few months, all that vegetation was flash-dried.

Kelley said those dry conditions made the Palisades especially susceptible to a fast-spreading fire.

This is part of a growing phenomenon that Swain calls "hydroclimate whiplash," or weather whiplash. As global temperatures rise, many parts of the world, especially California, are seeing more violent swings between extreme wet and extreme dry conditions.

The same confluence of weather whiplash and extreme winds was behind the Camp Fire, Swain said. That November 2018 blaze in Paradise, California, was the deadliest and most destructive in the state's history, destroying 18,804 structures and killing 85 people.