Weather Words: Zombie Fire

Similar to zombies you have seen on TV, zombie fires are the undead of the wildfire world, as they smolder beneath the surface all winter, waiting for the right moment to rise again.

Also known as holdover fires, zombie fires can be a huge challenge for firefighters, because they are very difficult to predict. While traditional wildfires are completely put out when their fuel is exhausted, embers can survive deep in the soil. Zombie fires can live underground for months at a time, relying on organic soils and decaying vegetation all winter long. They often survive under layers of snow, before emerging once again and igniting before humans and/or lightning strikes to create a fire in the traditional sense.

Scientists can track zombie fires using satellites, infrared imaging, and aerial surveys to detect heat anomalies in fire-prone areas before they erupt into full-scale wildfires. However, preventing and managing zombie fires is challenging. That’s because traditional firefighting methods, like creating firebreaks, may not be effective against a fire burning deep underground.

Jennifer Gray is a weather and climate writer for weather.com. She has been covering some of the world's biggest weather and climate stories for the last two decades.