While Wyoming has remained relatively quiet on the coal seam fire front so far this summer, the same can’t be said for just across the border in Montana.
There, temperatures are soaring past 100 degrees, and vegetation is drying into tinder, creating the perfect environment for smoldering underground coal to become raging wildfires.
The Remington Fire, which started in Wyoming last summer and became Montana's largest wildfire of 2024 at 196,000 acres, has left a combustible legacy.
Powder River County Assistant Fire Chief Clint Pedersen used a thermal imaging drone last month to survey the burn scar and identified 107 new burning coal seams.
Those underground fires now sit like unattended campfires waiting for the right wind to ignite new wildfires.
"We had one here the other day," Pedersen said of a recent 5-acre fire that sparked from a coal seam on Bureau of Land Management land. "It was on a coal seam that we knew about. Rough Red Shale, I think I called it."
There also are dozens of underground seams of coal in northeast Wyoming, which can smolder for years before something kicks them up to the surface. After hundreds of thousands of acres burned during last year’s wildfire season in the region, state and local wildfire officials have said many more may have been started.
Pedersen, who flies a drone equipped with a $25,000 thermal imaging camera, explained how shifting wind patterns can turn dormant coal seams into active threats.
"When we get a wind shift for a few days, you know, like it's been out of the west for quite a while, and then we get east wind or something, I think the vent holes become the exhaust hole," he said. "They switch directions and it's just glowing over the top of those intake holes now where they become exhaust holes. I think that that kind of flares them up."
Then there’s the curious role vegetation plays in the coal seam-wildfire relationship.
Sagebrush, yucca and trees serve as natural fuses once roots grow down to touch burning coal seams and create new ignition points.
"Most of the time I think it takes a root to burn down into the coal seam to start the coal seam," Pedersen explained. "Kind of like a forge, you know, the wind will blow down that hole at the root."
This creates what fire officials describe as a never-ending cycle: wildfires expose new coal seams, which then smolder underground until vegetation and wind conditions align to spark new fires, which in turn ignite more coal seams.
“This is one of our hottest burning coal seams that is close to the surface in southern Powder River County. It is probably close to 3000 degrees, which is what a forge operates at. Some of the deep ones are this hot but the ground surface temperatures are frequently 300 to 700 degrees,” according to CM Thermal & Fire LLC, which maps burning coal seams in southeastern Montana. (CM Thermal & Fire LLC) 
After an epic 2024 wildfire season burned vast areas across northern Wyoming and southern Montana, dozens of new burning coal seams are being revealed. In Montana, the Remington Fire burned almost 200,000 acres and left more than 100 new coal seam fires. (Lee Rentz via Alamy)
Tired Warden
For Custer County Montana Fire Warden Cory Cheguis, the relentless nature of coal seam fires is exhausting.
He recalls the aftermath of previous wildfires that exposed hundreds of new burning coal seams.
"I think it was somewhere over 300 new coal seams were reported in the Short Draw Fire," he said, referring to a blaze that burned along the Wyoming-Montana border. "Those are all unattended campfires, just sitting out there waiting for a windy day to take them away."
The Short Draw Fire began Sept. 11, 2024, north of Gillette, and quickly spread into Powder River County, Montana. The wildfire ultimately burned nearly 35,000 acres across both states, affecting state, federal and private lands.
The financial burden of permanently extinguishing these underground fires is staggering, said Cheguis.
"There's ways to actually put them out, but it costs money, you know, excavation," Cheguis explained, remembering how about 10 years ago several coal seam fires were permanently extinguished. “And it cost roughly — it was darn near $1 million. They actually excavated, hauled out the coal, filled in and then reclaimed ground."
The scope of the problem becomes even more daunting when considering the resources available to combat coal-seam fires. Cheguis is the only full-time paid firefighter covering Custer County's 3,793 square miles outside of Miles City.
"I'm the only paid position. Everyone else is a volunteer," he said. "We cover structure fire, wildland fire, hazmat, motor vehicle crash — that's a huge area.
"The volunteers are tired of dealing with this stuff, too. It's like, ‘Man, do you ever catch a break?’ We understand we're going to catch lightning fires. We understand we're going to catch human-caused fires here and there. But this coal seam fire plague — it's more like a full-time fire department job."
Quiet In Wyoming — So Far
Just across the border in Crook County, Wyoming, Fire Marshal Charlie Harrison described for Cowboy State Daily a markedly different situation.
"We've had three small lightning fires from this last wave of storms,” Harrison said, who was happy to report in the two years he’s been on the job, he hasn’t worked a fire ignited by a coal seam.
"I would assume that maybe there's some of that in the far west part of our county, but we've never had anybody say anything,” said Harrison.
Crook County is not part of a multi-county effort to map and monitor coal seam fires.
Campbell, Johnson and Sheridan counties are working to develop comprehensive mapping programs to identify and track these underground threats before they can ignite new wildfires.
David Madison can be reached at david@cowboystatedaily.com.
