T he fires burning in Southern California involve tens of thousands of acres — tiny in the context of all wildfires — and they moved with what might seem to some to be astonishing speed. In just 24 hours, the fire in the Pacific Palisades neighborhood of Los Angeles grew more than 15,000 acres. That’s several football fields a minute.
But fast-growing fires are now the norm. Using NASA satellite data, we studied more than 60,000 fires in the United States over nearly two decades. During that time, we saw a 250% increase in the average growth rate of fires in the United States. In California, we saw a 400% increase in how fast fires grew. In other words, fires are getting faster, more than doubling in speed nationwide and more than quadrupling in speed in California.
These are fearsome accelerations. And we found a relationship between the higher speed with which fires now move and the number of structures lost. Fires that grow by 4,000 acres a day often involve some loss of buildings. Fires that grow faster, by roughly 21,000 acres a day, typically destroy more than 100 buildings. The number of structures destroyed in Los Angeles County, more than 9,000, will likely keep growing.
Why are fires picking up speed? Our hunch is that just a little bit of warming can cause a lot more burning. But there are other factors, too.
We have indiscriminately built homes in the line of fire. Nearly 59 million American homes stood less than half a mile from wildfire between 2000 and 2024. Embers ignite homes, and these homes become the fuel to ignite other homes. As the number of homes on fire increases — essentially a series of mini-conflagrations all their own — fires quickly become impossible to fight. Aerial resources are grounded by smoke; with hundreds, if not thousands, of homes in a fire’s path, the risk to firefighters’ lives is simply too high to take.
Independent reporting for Pine Bluff & Jefferson County since 1879.
This is a particular crisis in the West, where Americans have been busy building at the edge — and often in the interior — of flammable forests, shrublands and grasslands, and often on hillsides. Odd as a winter fire in an urban area might seem, we expect to see more such disasters and more home losses in coming years.
What is to be done? We need to change how we think about our homes and neighborhoods. First, we need to retrofit and harden our homes against fire long before the flames arrive. Nature long ago adapted to fire: Long-living Ponderosa pine trees survive in part because their deeply creased bark dissipates the heat. Grasses have substantial underground roots that provide energy for them to resprout.
Homes can be made to do the same. Experts have fire-tested homes and buildings of various types and are showing us how to live with fire, rather than be overwhelmed by it.
With as little as a few thousand dollars, owners can retrofit a home to lower the risk of ignition. In fact, it costs about the same to build a new fire-resistant home as it does to build a new home with no wildfire adaptations. Remove shrubs, bark mulch and other combustible materials that stand within five feet of the home. Homes can ignite if vents are not properly screened with mesh to prevent wind-driven embers from entering an attic or crawl space. And though most homes are ignited by embers (and not a wall of flames from nearby trees), it is important to trim nearby and overhanging limbs.
Some communities in the West, especially in places where a home in the woods or overlooking a lake or a pristine valley is highly desired, are scaling up efforts to do the mitigations that matter. In Lake Tahoe, fire mitigation experts are assessing every home once every three years and expending nearly $4 million a year on community wildfire resilience. At the state level, there are efforts to support homeowners to do the retrofits, provide tax credits or grants for the work. Currently, national-level fire risk assessments do not account for fire speed, but they need to.
Americans also need to be much more realistic about their vulnerabilities. There are now many one-road-in, one-road-out neighborhoods near or in mountain-state towns that live with impossibly high wildfire risk. Many of these neighborhoods did not exist a decade ago, and others are overcrowded as residents seek to be close to nature. Residents must think about escape routes in advance and always be ready to go.
In short, we need to prepare. By the time a fast fire ignites, it is too late. To support firefighters and protect our communities, we need to be ready long before fire comes.
Jennifer Balch is a fire scientist and director of the Environmental Data Science Innovation and Inclusion Lab at the University of Colorado at Boulder. Ralph Bloemers is director of fire-safe communities for the Green Oregon Alliance.