AILSA CHANG, HOST:
This summer has brought terrible fires to Montana. And meteorologists say they now know why - a flash drought. Yellowstone Public Radio's Nate Hegyi explains.
NATE HEGYI, BYLINE: Leaning on a pickup truck in a fire camp in Sand Springs, Mont., rancher Matt Bliss looks out at a low, hazy horizon. He's wearing a yellow fire jacket. And he says most of his nearby range land is completely burned.
MATT BLISS: It's tough to see it black. I mean, all the trees black - and all the ground black. It's a disaster area. It's just - wow, it is so hard to see when you...
HEGYI: The nation's largest wildfire scorched an area the size of New York City here. And like the other fires burning in Montana right now, it was spurred by what meteorologists are calling flash droughts.
TANJA FRANSEN: It's a drought that comes on very quickly.
HEGYI: Tanja Fransen is with the National Weather Service in Montana. She says over the past few years, it's rained and snowed a lot in eastern Montana. There were record floods, storms. And all the brush grew really big and thick. But then this spring, no rain came. Temperatures hit triple digits. And within a few weeks, all that brush turned brown and brittle. And now it's so dry, Fransen says, a single spark from a horseshoe striking a rock could cause a fire.
FRANSEN: It's the driest in 110 years up in this area.
HEGYI: Fransen says these flash droughts - and there are actually two of them, a severe one in the east and a milder one in the west - aren't caused by normal climate patterns like El Nino or La Nina.
FRANSEN: Seeing more extremes is something that people probably need to be getting used to and work on some resiliency with that.
HEGYI: A federal climate report says the Northern Great Plains are nearly two degrees warmer than they were during the first half of the century. And rancher Sarah Browning says she's never seen a fire like the one that burned most of her range land. It jumped across rivers and exploded cottonwood trees. It raced towards her house.
SARAH BROWNING: And it just covered us. And it was daylight out. And it just turned black. You couldn't see right in front of you. And when it started lifting, in a matter of just two minutes, the whole valley was on fire.
HEGYI: Montana is spending about a million and a half dollars a day battling wildfires. It's the worst season the state has seen in years. And while people can aggressively clear brush around their houses, given the size of the state, things grow. They die. And now they're burning. For NPR News, I'm Nate Hegyi in Sand Springs, Mont. Transcript provided by NPR, Copyright NPR.