Hot drought increased the occurrence probability of the 2025 Los Angeles destructive wildfires

The western Los Angeles (LA) wildfires in early January 2025 caused catastrophic social and environmental impacts, attracting widespread attention. In this study, we investigated the characteristics of these wildfires and quantified the influence of drought and hot conditions on their likelihood using a Copula-based Bayesian probability framework. The wildfires were characterized by their burned area (BA) and intensity (Fire Radiative Power), and hot drought was identified using 5-day Standardized Temperature Index and 75-day Standardized Precipitation Index, respectively. The wildfire outbreak began on 7 January and burned for more than 6 days, with a total BA of over 245 km2 and cumulative intensity of >41,060 MW. Using satellite-derived active fire observations from 2001-2025, we estimated that the occurrence of such large and intense wildfires during LA’s rainy season was a once-in-67-year event. The wildfires were largely driven by hot drought conditions, which dried out the soil and vegetation that had been promoted by above-average precipitation in the previous winter seasons, thereby providing abundant fuels to burn. Our analysis of wildfires across all seasons reveals that extreme drought increased the probabilities of wildfires with intensity and BA in 2025 by 54% and 75%, respectively. Hot drought further amplified these probabilities by 149% and 210%. The findings suggest increased large-fire risk under hot drought conditions, which expanded the wildfires to the non-traditional fire season.