St. Louis ? The worst U.S. drought in decades got worse in parts of the nation’s midsection, further frustrating ranchers and growers of winter wheat in Kansas and Oklahoma, a drought-tracking consortium’s update showed Thursday.

The U.S. Drought Monitor’s latest map showed that 60 percent of the land in the lower 48 states was experiencing some degree of drought as of Tuesday, down less than a percentage point from the previous week. Nearly one-fifth of the contiguous U.S. remained in extreme or exceptional drought, the two worst classifications.

But the stubbornly dry conditions intensified in Kansas, the top U.S. producer of winter wheat. Thursday’s update, put out by the National Drought Mitigation Center at the University of Nebraska in Lincoln, showed that the expanse of that state in extreme or exceptional drought climbed roughly 6 percentage points, to 83.8 percent.

Three-quarters of hard-hit Oklahoma — another key winter wheat state — is mired in the two highest forms of drought, up 8 percentage points from the previous week. The Oklahoma Mesonet, a statewide network of environmental monitoring stations, said that 18 of its stations recorded less than one-tenth of an inch of rainfall in October, while 66 measured less than an inch.

“The combination of warm and dry weather was taking a toll on grasses and small grains” such as winter wheat, which as of Monday was running out moisture, David Miskus, a senior meteorologist with the Climate Prediction Center, wrote in authoring Thursday’s report.

Thirty percent of Oklahoma’s fledgling winter wheat crop was found to be in poor to very poor shape, a decline of 18 percentage points from the previous week, as topsoil moisture in the state continues to grow increasingly parched.

“With so much of Oklahoma already in (extreme or exceptional drought), it is getting difficult to degrade the state further,” Miskus wrote.

Ninety-five percent of Nebraska and half of Iowa remained in the two worst drought categories, Thursday’s update showed.

Conditions continued improving some states, such as Arkansas, where the amount of land in extreme or exceptional drought fell nearly 6 percentage points to 29.8 percent.

With the nation’s harvest of corn and soybeans nearly completed, Midwest farmers have turned their attention to their winter wheat, with little cooperation from the weather as about two-thirds of those plantings have taken place in drought-affected areas.

Some 92 percent of the nation’s winter wheat is now in the ground, on pace with the average planting speed over the previous five years, according to the U.S. Department of Agriculture. Seventy-three percent of the latest crop has emerged, consistent with the showing during the past half-decade.

Thirty-five percent of the U.S. winter wheat plantings are considered good while 42 percent are deemed fair. Nineteen percent of the crop is classified as poor or very poor.

Climate watchers haven’t anticipated meaningful precipitation that would appreciably relax the grip of drought that has put soil moisture and levels of rivers and reservoirs used for irrigation at such a deficit.

Farmers embrace snowfall as a means of recharging soil moisture in time for each spring’s corn and soybean sowings, with about 20 inches of snow equating to just an inch of actual water.