HELENA — The drought plaguing eastern Montana and much of North and South Dakota came on quickly and is intensifying, leading ranchers to sell their cattle and farmers to harvest early whatever crops that have grown so far this summer.

Just three months ago, no areas of moderate drought were recorded in the Northern Plains region by the U.S. Drought Monitor at the University of Nebraska-Lincoln. But July’s soaring temperatures and lack of rain quickly parched the soil and dried up waterways, creating what climatologists call a “flash drought.”

Now, 62 percent of North Dakota, more than half of South Dakota and 40 percent of Montana are in severe, extreme or exceptional drought, according to the drought monitor’s weekly report released Thursday. There are also pockets of drought in the Southern Plain states of Nebraska, Iowa, Oklahoma and Texas.

In Montana, 12 percent of the state’s land is experiencing “exceptional drought,” meaning widespread crop and pasture losses and water-shortage emergencies, mainly in the northeastern part of the state.

“We would expect to see conditions that bad once or twice in 100 years,” said Deborah Bathke, a climatologist at the University of Nebraska-Lincoln’s National Drought Mitigation Center and a co-author of the drought monitor.

The effect has been devastating on farmers and ranchers. Farmers are harvesting beans, peas and lentils two or three weeks earlier than normal, with a yield of about half of what they see in a normal year, said Lola Raska of the Montana Grain Growers Association.

Wheat crop yields are even worse, coming in at about a third of normal, she said.

“A lot of wheat prices are still very low,” Raska said. “That, in addition to low yields, is going to have a ripple effect throughout the entire economy.”

Jay Bodner of the Montana Stockgrowers Association said the extreme drought means ranchers are running out of pasture and water. They are reducing their herds by selling older cows and weaning and shipping young calves early.

It could take years for ranchers to build their herds back up, meaning extended economic losses, Bodner said.

“These high temperatures in July deteriorated things really quickly,” he said. “We typically don’t see those severe conditions.”

The region saw more than 20 days in July with temperatures exceeded 90 degrees, according to the National Weather Service. Rainfall for the month ranged from trace amounts in eastern Montana’s Miles City to 1.68 inches (4.27 centimeters) in Bismarck, North Dakota.

Half of Montana’s 1.5 million head of cattle are in drought areas, according to the U.S. Department of Agriculture. U.S. government officials have opened more federal land to grazing and water is being trucked in, but those are temporary fixes, Bodner said.

The drought also made the land more vulnerable to wildfires. Montana’s largest fire devastated more than 420 square miles of farm and ranchland in eastern Montana, compounding the problems for growers in the region.

The outlook is grim with the National Weather Service’s Climate Prediction Center’s predicting the drought will last into the fall, with higher-than-normal temperatures and low precipitation expected.

That could force farmers to delay fall planting and ranchers to make more cattle reductions.

“If these conditions persist well into the fall, it will have ramifications of some more magnitude,” Bodner said.