Holdover fires: How can flames resurrect a year later?

ROGUE RIVER-SISKIYOU NATIONAL FOREST, Ore. — After a “holdover” from the Klondike Fire in Josephine County flared back up this past weekend, fire officials said it’s not uncommon to have holdover fires in areas burned from the previous year.

They said even with the good winter we had, fires can still burn underground, hidden from the naked eye. The warm ground beneath the surface combined with the warm, dry weather of summer creates the perfect formula for resurrecting a wildfire.

A fire needs three things to ignite and keep burning: heat, fuel and oxygen. The further into the ground you go, the warmer it gets—creating heat. Things like tree roots, dead vegetation and buried logs are the fuel. Then when you have tiny pockets of oxygen underground, you’ve got a fire no one can see.

“As it warms up, that little heat source, maybe a buried log or root system, it starts to combust again,” said Rogue-River Siskiyou National Forest Fire Staff Officer Eric Hensel. “Once it comes in contact with some burnable vegetation, then it just can rekindle and start the fire up again,” Hensel said.

Experts say when this happens, there isn’t much crews can do about it until it comes to the surface. “Most oftentimes they’re not as much of a threat as a new wildfire that might start in an area that’s not been burned,” Hensel said, “where you have lots of continuous fuel that could feed the fire for a long time.”

Skip to content