KANSAS CITY: Extreme drought doubled its grip on the top US corn- and soybean-producing state of Iowa in the past week, a report by climate experts showed on Thursday.

The area under extreme drought in Iowa rose dramatically to 69.14 per cent from 30.74 per cent a week ago.

Drought expanded in other important farm states over the last week as well, to 94 per cent of Missouri and more than 81 per cent of Illinois for at least “extreme” conditions -- the second-highest rating, after “exceptional.”

“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, part of the consortium that issued the report.

Moving out of summer and into fall, the weather pattern still looks mostly dry for these Midwest and Plains states, with thin chances of substantial rainfall in the near term, he said.

“We have sort of reached the apex. We are way behind the 8 ball here,” Svoboda said.

The drought has been worsened by scorching temperatures. July turned out to be the hottest month on record in the continental United States, beating the one recorded in July 1936, the National Oceanic and Atmospheric Administration (NOAA) said.

The January-July period was also the warmest since modern record-keeping began in 1895. The year to end-July was the warmest 12-month period, eclipsing the last record set a month ago. It was the fourth time in as many months that US temperatures broke the hottest-12-months record, according to the NOAA.

“The heat is so intense. When you have conditions like that, even if you pick up a rain event you are taking so much moisture out so rapidly,” said Brian Fuchs, climatologist with the National Drought Mitigation Center.

In the Plains, the pattern of excessive heat and dryness also persisted, with drought expanding across Nebraska, Kansas, Oklahoma and parts of Texas.

More than 96 per cent of Oklahoma, more than 91 per cent of Nebraska, and more than 89 per cent of Kansas is in extreme drought. Water emergencies and shortage concerns in several communities have been cited.

Arkansas, considered part of the US South, is one of the hardest-hit states, with more than 53 per cent of the state in exceptional drought. A week ago, 44.46 per cent of Arkansas was rated in exceptional drought. More than 96 per cent of the state is in severe drought.

The high heat and lack of soil moisture have decimated the US corn crop and threaten 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 per cent from 14 per cent, according to government data.

The US soybean-growing area suffering from extreme and exceptional drought rose to 50 per cent from 16 per cent.

Light rainfall this week in parts of the Midwest will provide only minimal relief, crop experts said. US 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.

US corn futures prices soared 1 per cent to near record highs early on Thursday and new-crop December futures set a contract peak. Corn prices rose almost 23 per cent in July and international wheat prices have followed, gaining about 19 per cent.

The price hikes and fears of drought-hit harvests of new crops have triggered warnings from the United Nations of costlier food and potentially a crisis.

“The overall damage from drought has been significant,” Fuchs said.