Holdover wildfires can smolder underground in vegetation or root systems and later reignite, potentially days after the initial ignition.
October 23, 2025
high
behavioral
Describes a persistent wildfire behavior in which subsurface smoldering can lead to delayed re-ignition.
Smoldering fires in root systems can reach depths of approximately 15 to 20 feet (4.6 to over 6 meters), which can make them undetectable by thermal imaging cameras.
October 23, 2025
high
technical
Provides a detection limitation for subsurface smoldering fires relevant to firefighting and remote sensing.