And the drought is worsening in the South, which was just recovering from last year's drought - the worst Texas had seen in a century.

Almost 30 percent of the nine-state Midwest was suffering extreme drought, nearly triple from the previous week, according to the U.S. Drought Monitor for the week ending July 24.

Conditions in the Midwest, which produces roughly three-quarters of the corn and soybean crops in the world's largest producer and exporter, worsened despite the first measurable rainfall in a month in some areas.

More than 53 percent of the United States and Puerto Rico are in moderate drought or worse, a record-large amount for the fourth straight week in the Drought Monitor's 12-year history.

"The two-plus inches (of rain) from southern Wisconsin to northern Indiana was able to only maintain status quo. Most other areas were not as lucky," said Drought Monitor author Richard Heim of the National Climatic Data Center.

"Pasture, rangeland, and crop condition continued to deteriorate from the Colorado High Plains to the Ohio- and mid-Mississippi valleys, and from Oklahoma to the Dakotas," he said.

More than half of the country's pastures have been rated poor or very poor by the U.S. Agriculture Department, while the corn and soybean crops have wilted under scorching temperatures during their more vulnerable periods of pollination.

In the South, extreme and exceptional drought conditions increased in Texas, Oklahoma and Arkansas, even as the overall area in the region affected decreased slighty.

A Reuters poll this week estimated the U.S. corn yield at 130.8 bushels per acre, the lowest in 10 years.

"For a lot of the hardest hit areas, it's too late to reverse the damage on corn. We had a lot of stress ahead of silking and into pollination, and that's the worst time we could have that stress," said Jefferies Bache grains analyst Shawn McCambridge.

The parched conditions propelled corn and soybean futures to record peaks last week at the Chicago Board of Trade before scattered rains this week took prices off their highs.

Surging animal feed prices -- the biggest input costs for livestock producers -- also led some farmers to cull their herds in the main cattle producing region of the Plains.

Light showers overnight in the southwestern Midwest were too little too late to prevent further losses in the crops, while heat of 100 degrees Fahrenheit (38 degrees Celsius) or higher was forecast to continue into next week, Andy Karst, meteorologist for World Weather Inc, said Thursday.