Access the interactive map at https://fuelwatch.ctrees.org/ (opens in a new tab)
On Wednesday, the National Weather Service issued a red flag warning for large areas of Southern California, indicating high fire risk across the region due to Santa Ana winds, dry conditions, and high heat. Local and state agencies have activated emergency plans and fire crews are now battling a fire in Malibu.
While the red flag warning covers a broad region, a new map from CTrees narrows the view of risk to the specific slopes, canyons and communities in Los Angeles County where a spark is most likely to spread into out-of-control wildfire.
The map is part of a new CTrees system, Fuel Watch, that tracks live fuel moisture, the water content of living vegetation, at 30-meter resolution for any area of the western U.S. on a weekly basis. Each cell covers roughly the area of two basketball courts.
With updates since March, the maps for Los Angeles County give a clear picture of how fire risk has evolved over time. It then overlays current wind patterns to identify this week’s highest-risk areas.
The Fuel Watch map is now available at: https://fuelwatch.ctrees.org/ (opens in a new tab).
The findings are stark. Live fuels have dried sharply since the wet spring, and 93% of chaparral ecosystems now register fuel moisture levels in CAL FIRE’s high fire risk threshold.
Monitoring fuel moisture for wildfire prevention
Early detection systems have become much better at spotting fires the moment they ignite. Early warning acts sooner. By tracking how fuel load and moisture changes over time, agencies and communities can pre-position crews, target fuel reduction, and limit fire spread in the most vulnerable areas before an ignition occurs.
Today, Los Angeles County agencies and utilities monitor fuel moisture at ground levels. Crews clip chamise, the most common chaparral shrub, at multiple sites, and weigh the samples to determine moisture levels. While highly accurate, such approaches are costly and difficult to scale across a large landscape.
Fuel Watch fills this gap. CTrees trained the system on western U.S. field data up to 2023, combining multiple satellite data that observe vegetation water content at different resolutions and revisit time in an advanced AI model. The model estimates match local ground measurements, while extending low uncertainty predictions across the whole landscape.
“Our slogan is ‘Predict, Prepare, Prevent,’” said Sassan Saatchi, CTrees’ CEO and chief scientist and a senior research scientist at NASA Jet Propulsion Laboratory/Caltech. Saatchi leads the project with research scientists Zhihua Liu, Chris Mihiar, and postdoctoral fellow Bryan Shaddy.
“The system provides information that people can use to prepare for wildfire risk. We look forward to working with agencies and communities in Los Angeles, and across the U.S. to make live fuel moisture mapping a part of their fire response,” Saatchi said.
The system is now in demonstration, and can be applied to any region across the western U.S. The model can map wildfire risk in near real time at resolutions down to 10 meters. It also distinguishes moisture at the surface from moisture in the canopy, guiding actions for treatments and prevention.
Agencies and organizations interested in working with CTrees can reach out at info@ctrees.org or via our contact form (opens in a new tab).
Contact: Daniel Melling, director of marketing and communications, dmelling@ctrees.org.
