Suselj, K., Kurowski, M., Samuels, B.D., Kahn, B.H., Chinita, M.J., & Teixeira, J. (2025) ‘Coupled weather-fire simulation of the 2025 Eaton Fire at the wildland-urban interface.’ ESS Open Archive. doi: 10.22541/essoar.176384759.95874166/v1 [preprint]

Abstract

The 2025 Eaton Fire in the San Gabriel Mountains, California, provides a compelling case to investigate the dynamics of wind-driven wildfires over the complex topography at the wildland–urban interface (WUI). Fueled by intense Santa Ana winds, low humidity, and dry fuels, the fire rapidly spread into urban neighborhoods, causing extensive damage. We used an atmospheric model at Large Eddy Simulation (LES) scales (~100 m grid spacing) for simulation of flow dynamics over complex, realistic terrain, driven by weather reanalysis and coupled to a fire propagation model. To accurately capture observed fire behavior, particularly across heterogeneous landscapes, we implemented targeted modifications to default fuel characteristics that are often used by fire models. For better representation of the urban environment, we introduced two new fuel types, one representing buildings and the other one suburban landscaping. This modification allows the model to realistically capture when the fire crossed from wildland into urban areas. We also modified fuel characteristics over recent burn scars as these areas act as natural barriers for fire spread. This study demonstrates the feasibility of explicit, high-resolution coupled weather-fire simulations for accurately modeling complex WUI fires. We establish a framework for supporting operational forecasting, mitigation planning, and targeted urban wildfire risk assessment in areas characterized by complex terrain and extreme fire-weather conditions.