A preliminary investigation from the U.S. Forest Service has found a hold-over lightning strike to be the likely cause of the Bridger Foothills Fire.
In an update posted on the Custer Gallatin National Forest Facebook page on Friday, the Forest Service said the investigation, completed with support from the Gallatin County Sheriff’s office, included interviews with first-account observers, detailed fieldwork, and analysis of weather data, among other factors.
The Forest Service said in the post a hold-over means "the actual ignition of the fire likely occurred during a storm late August that produced extensive lightning over Bozeman and the Bridger Mountains."
The fire stayed dormant until several days of warmer temperatures brought it to life on Sept. 4, the Forest Service said on Facebook.
“It’s very common for fires to appear several days to weeks after a lightning storm has passed through,” said District Ranger Corey Lewellen.
The Forest Service said crews responded to another fire north of the Bridger Foothills Fire earlier that same Friday that was also found to be a hold-over from the same storm.