In the past week, extreme drought doubled its grip on the top corn and soybean producing state of Iowa, according to a report by a consortium of climate experts issued Thursday.
The area under extreme drought in Iowa rose dramatically to 69.14 percent from 30.74 percent a week ago.
Drought expanded in other important farm states over the last week as well, to 94 percent of Missouri and more than 81 percent of Illinois for at least extreme drought.
"Every day we go without significant rain ... is tightening the noose," said Mark Svoboda, a climatologist with the University of Nebraska's National Drought Mitigation Center.
Moving out of summer and into fall, the weather pattern still looks mostly dry for these Midwest and Plains states, so chances of substantial rainfall in the near term are thin, he said.
"We have sort of reached the apex. We are way behind the 8 ball here," said Svoboda.
The drought has been made worse by scorching temperatures. July turned out to be the hottest month in the continental United States on record, beating the one recorded in July 1936, the National Oceanic and Atmospheric Administration (NOAA) said.
The January-to-July period was also the warmest since modern record-keeping began in 1895, and the warmest 12-month period, eclipsing the last record set just a month ago. It was the fourth time in as many months that U.S. temperatures broke the hottest-12-months record, according to NOAA.
The high heat and lack of soil moisture has decimated the U.S. corn crop and is threatening the same to the soybean crop.
In the last three weeks, the amount of corn-growing farmland suffering extreme and exceptional drought expanded to 53 percent from 14 percent, according to government data. The U.S. soybean growing area suffering from extreme and exceptional drought rose to 50 percent from 16 percent.
Crop condition ratings for corn and soybeans have fallen to the lowest since the major drought of 1988, propelling prices of both crops to all-time highs last month.
In the Plains, the pattern of excessive heat and dryness also persisted, with drought expanding across Nebraska, Kansas, Oklahoma and parts of Texas. Water emergencies and shortage concerns in several communities have been cited.
The only real area of improvement this week was in the Black Hills of South Dakota, where generally cooler weather was noted.
(Editing by John Picinich)