Saturday, November 22, 2025

New Report Reveals How SoCal Fires Became “Urban Conflagrations,” Causing 32 Fatalities

A new report on the devastating January 2025 Southern California wildfires, which led to 32 confirmed fatalities, concludes that the blazes rapidly transformed from typical wildland events into fast-moving “urban conflagrations” fueled by homes and vehicles. The Southern California Fires Timeline Report, released on Thursday, November 20 by the Underwriters Laboratories Fire Safety Research Institute (ULRI), provides a detailed timeline of the fires that burned between January 7-31, with a focus on the Eaton Fire that ravaged parts of Altadena and Pasadena.

The report serves as the foundation for Phase Two, the Southern California Fires Incident Analysis Report. The analysis in the second report will look to understand pre-existing conditions in the fire areas, the influence of the built environment on fire behavior, first responders’ actions, and emergency response agencies’ capabilities for addressing urban conflagrations.

The second report will also include detailed recommendations to improve emergency preparedness and response and will be available for implementation by the State of California, local officials, and communities.

Commissioned by the Office of the Governor of California, the Phase One report offers a critical first analysis of the 12 fires that swept across Los Angeles and southern Ventura counties. Its most significant finding is the documentation of extensive structure-to-structure fire spread. Unlike traditional wildfires fueled by vegetation, the January fires were characterized by their rapid intrusion into urbanized areas where the primary fuel source became the built environment itself: homes, commercial buildings, and cars. This dangerous shift was accelerated by a combination of extreme weather and environmental conditions.

The Eaton Fire, which began at 6:18 p.m. on January 7, directly impacted the communities of Altadena, Pasadena, Sierra Madre, and Malibu. According to the ULRI report, the region was primed for disaster. Months of severe drought had left vegetation at critically low moisture levels. This was exacerbated by the arrival of powerful Santa Ana winds, which reached “hurricane-force” speeds, and temperatures soaring to around 102°F. These conditions allowed the fires, which originated in the foothills, to be driven by wind-blown embers deep into developed areas, overwhelming initial firefighting efforts.

The report meticulously documents the timeline of the Eaton and Palisades fires, drawing from a wide range of sources, including direct field observations and data from local and state fire agencies. However, it is important to note that this report is a timeline of the fires’ progression and, as stated in the document, does not include an analysis of the fires’ origin-and-cause, which are being conducted separately by jurisdictional fire departments.

While this Phase One report focuses on the timeline of the fires, the forthcoming Southern California Fires Incident Analysis Report (Phase Two) will delve deeper into the performance of fire protection systems, the effectiveness of evacuation efforts, and provide science-based recommendations for improving community resilience.

For the residents of Altadena and Pasadena, the ULRI report is a critical document. It provides the first official, in-depth analysis of a disaster that directly impacted their community. By detailing how a wildland fire transformed into an urban conflagration, the report offers a stark warning about the evolving risks at the wildland-urban interface. The findings will undoubtedly shape future discussions about building codes, land use planning, and emergency preparedness in the region.

The report may be found online by clicking here.