Why wildfires are becoming faster and more furious

On Tuesday morning, January 6th, a “life-threatening and destructive” storm was bearing down on the northern suburbs of Los Angeles, with terrible timing. The local office of the US National Weather Service issued a strongly worded alert at about 10:30 a.m. local time. Almost at that exact moment, a fire broke out in the Palisades neighborhood of Los Angeles.

“The fire was able to start and get a foothold, and then the wind came and pushed it really hard. It’s really the worst-case scenario,” said Allie Graydon, co-chief executive of RedZone Analytics, which makes wildfire modeling products for the insurance industry. The fire spread rapidly, and other wildfires broke out in nearby areas. Thousands of homes and other buildings were leveled, and Sunset Boulevard was left in ruins. At the time of writing, the Los Angeles fires had caused at least 10 deaths, and officials had ordered the evacuation of nearly 180,000 people.

The fires are now considered to be among the most destructive in Los Angeles’s history, with some estimates of the damage ranging from $52 billion to $57 billion. It is not yet known how the Los Angeles fires started, but most wildfires are human-caused. Possible ignition sources include lightning strikes, downed power lines, carelessly discarded cigarettes, or even more sinister causes such as arson. While authorities in Los Angeles begin to piece together the cause of the initial blaze, the speed with which the initial flames grew into a raging inferno reflects a wider phenomenon.

In this case, a confluence of environmental conditions combined with disastrous timing. A long drought and heavy rains in the days before provided the fuel, while strong, sometimes hurricane-force winds fanned the flames into an inferno. Initially, powerful gusts of wind known as Santa Ana winds blew from inland toward the coast, reaching speeds of up to 80 miles per hour (129 kilometers per hour), which intensified the fires. Unfortunately, the high winds prevented some fire-fighting helicopters and planes from taking to the skies to dump water on the burning areas.

“Without air support, we’re basically playing ‘whack-a-mole’ to prevent losses at specific locations,” Ms. Graydon said. These circumstances are unfolding against a backdrop of climate change, which is not only increasing the risk of wildfires around the world, but also making them more explosive. When relatively small fires suddenly “blow up,” the speed is so fast and the intensity so great that they become difficult to control. Some models estimate that human-caused climate change has increased the risk of such rapidly spreading fires in California by about 25%.

Matt Jones, a earth systems scientist at the University of East Anglia who studies the impact of climate change on wildfires, points out that Los Angeles had unusually high rainfall in both 2022 and 2023. During this period, downtown Los Angeles received 52.46 inches (133 centimeters) of rain, nearly a record. The excessive rain helped vegetation in the area to grow, but in 2024, the weather changed. Last year was very dry compared to the two previous years. This means that there is now a lot of dry vegetation scattered around Southern California. “We’re facing a very explosive situation,” Mr. Jones said.

The influence of Santa Ana winds is also significant. Santa Ana winds go by different names depending on where you are. In the Alpine regions of Germany, Austria, and Switzerland, they are known as foehn or fohn winds, and in folk beliefs, they are associated with a range of symptoms, including migraines, depression, insomnia, confusion, and an increased risk of accidents. A 1911 report published in a scientific journal revealed the dramatic impact of foehn winds in Innsbruck, Austria: “This wind often blows with great force, and unless one closes the windows in time, everything in the house is quickly covered with a thick layer of dust.”

Climate change is creating hotter conditions in some of the areas that experience similar Santa Ana winds, meaning that the impacts or potential consequences—particularly in terms of rapidly escalating wildfires—are worsening. According to some studies, these winds are becoming more prevalent in some parts of the world because of climate change. This increase could have a profound impact on wildfires. For example, in Switzerland, researchers found that fires burned three times as much area on days with foehn winds than on days without. Fires that spread very quickly are particularly dangerous, not only because of the threat to human life and property, but also because the area these fires can cover can be so extensive.

A study published last year investigated the frequency of sudden, escalating “blow-up” fire events. Significantly, those fires that burn intensely in a relatively short period of time end up burning much larger areas. “Single-day extreme fire spread events are disproportionately shaping the North American landscape,” the authors wrote. They estimated that, between 2002 and 2021, fires in North America that burned more than 1,704 hectares (4,210 acres) in a single day burned an average of 2.3 million hectares (5.7 million acres) annually. The study suggested that the Mediterranean region of California, where Los Angeles is located, is particularly prone to rapidly escalating, large-scale fires.

While downslope Santa Ana winds appear to have accelerated the Los Angeles wildfires, very different conditions can also cause fires to blow up. Mr. Jones said that wildfires can sometimes create their own weather, even without strong winds. “They create their own intense local winds, which can affect the speed of fire spread, and also trigger unstable changes in direction,” he explained. When a fire heats the air above it, it creates powerful updrafts, which are strong enough to form huge cumulonimbus clouds high in the sky. Research published in 2021 found that the appearance of such clouds can be an indication that a wildfire is about to escalate rapidly, or that the process has already begun. These storm clouds can trigger lightning strikes, which may ignite more fires nearby.

The interplay between wind and fire is a common theme. John Abatzoglou, a climatology professor at the University of California, Merced, explained: “In certain parts of the planet, you can get rapid growth in fires during the passage of a frontal system—which is basically a weather system that gives you wind but not rain.” Professor Abatzoglou said that, in the absence of Santa Ana winds, fires tend to spread uphill, but in places like California, Santa Ana winds can push fires downhill. Similar downslope winds are also believed to have played a role in the deadly wildfires on Maui, Hawaii, in 2023. In any case, when rapidly developing fires occur near towns and cities, they can be very tricky. Speaking about the situation in Los Angeles, Professor Abatzoglou said, “It only takes a few hours to go from ignition to impacting a lot of people.”

One contentious issue, particularly in densely populated areas such as California, is whether it is still safe to live so close to these disaster-prone areas. In recent years, insurance companies have gradually pulled out of the state, reducing the number of policies available to homeowners, although last month the California Department of Insurance issued a landmark regulation designed to make insurance more accessible. Some residents are also looking into ways of trying to fireproof their homes. Those with the greatest resources might take inspiration from the Getty Villa in Pacific Palisades. (Although perhaps not without a touch of irony. The museum was originally built by the early 20th-century oil tycoon J. Paul Getty.) Staff regularly prune the trees and shrubs in the gardens to ensure that there is no excess vegetation to fuel a fire. The building’s galleries also have double walls, and staff can control the flow of hot air into the villa to some extent through the air conditioning system.

But fires can jump for miles, which makes them difficult to control. Embers from burning vegetation can be picked up and carried by the wind, causing new fires to ignite some distance away. Many homes catch fire not from direct contact with flames, but because embers can fly for miles, entering through the eaves or gable vents. Homeowners can replace porous vents with fire-resistant vents, which are designed to prevent wind-blown embers from getting in, and install ember-proof gutter guards, which allow rain to enter, but stop vegetation from building up on the roofline. Although some Los Angeles mansions are palatial, many, including several belonging to celebrities, have been destroyed in recent fires. The biggest wildfires can overwhelm even the most robust homes.

Los Angeles is indeed making efforts to reduce the risk of large-scale fires. For example, the city hires goats to allow the animals to graze on the shrubs on hillsides. “We’ve been overwhelmingly welcomed wherever we go,” said Michael Choi, a herder, in a recent interview. “As far as I know, it’s a win-win.” There are also efforts to use surveillance systems based on high-tech cameras to monitor developing wildfires, as well as attempts to use supercomputers to predict when fires are most likely to occur. That said, these systems were put into use in Los Angeles last week, but this did not prevent the recent fires from taking lives and leaving large areas in ruins. Ms. Graydon said that homeowners living in fire-prone areas need to consider their own vulnerability: “It’s not just a seasonal risk anymore. It’s a risk that people need to take seriously all the time.” She recommends clearing vegetation around homes as much as possible, and installing fire-resistant roofs or sprinkler systems. Having an evacuation plan can also save lives.

When the work of repairing and rebuilding homes in Los Angeles eventually begins, some people may turn to using fire-resistant materials, such as bricks made from earth. But at the heart of the matter is a deeper problem. Margaret Klein Salamon, a climate activist and the leader of the Climate Emergency Fund, a non-profit organization that funds climate activism, argues: “We built our civilization in a climate [that was], and now we’re fundamentally changing [that climate] by burning fossil fuels.” She added: “Unless we make major changes, this is what the future looks like,” arguing that the problem of climate change will not simply disappear by relocating from some of the worst-affected areas.

As the world becomes hotter and rainfall patterns become more erratic, we are likely to see fires like those in Los Angeles break out more frequently. Mr. Abatzoglou highlighted the wildfires in Chile and Greece in 2024 as key examples of how very dry conditions set the stage for disaster. In 2023, fires hit Canada, burning an area larger than England, and these fires were also fueled by high temperatures and drought. Mr. Abatzoglou pointed out that climate change is bringing dangerous changes. The shifts in weather that we are seeing in Southern California, from periods of heavy rain to suddenly hot, dry, fire-inducing conditions—known as “hydroclimate whiplash”—are clearly very problematic. “I think what’s really important in terms of fire are these sequences,” Mr. Abatzoglou said. “The rapid shifts from unusually wet to unusually dry. That’s what we’re seeing across the globe.”