The midday forecast showed that for next week, the eastern Midwest would get "less than 0.25 inch of rain" — down from the morning forecast which called for up 0.75 inch rain, said Drew Lerner, meteorologist for World Weather Inc.

Lerner said the atmospheric high pressure ridge was locked over the western Plains and western Midwest and was poised to remain stable, blocking moisture from entering the crop belt and leading to a buildup of heat.

"It's the same old song and dance," Lerner said.

Temperatures will rise into the upper 90s (degrees Fahrenheit) to low 100s F early this week, cool to the 80s F by midweek then rise into the 90s F again by the weekend, said John Dee, meteorologist for Global Weather Monitoring.

"There are no sustainable soaking rains in sight. There is some slight relief but no huge reversal in the drought," Dee added.

Commodity Weather Group (CWG) on Monday said more than one-half of the Midwest would still be too dry and warm for at least the next two weeks and the most persistent heat was expected for the western Midwest.

"This will leave over one-half of the late-pollinating and filling corn and pod-setting soybeans subject to additional stress," CWG meteorologist Joel Widenor said.

CWG's Monday report said the drought was more focused on southern Wisconsin, western Illinois, southern and western Iowa, far northern and far western Missouri, southwest Minnesota, South Dakota, Nebraska and Kansas.

Until now, the devastating drought has been decimating corn and soybean crops in the southern Midwest and eastern Midwest in states such as Arkansas, Kentucky, Indiana, Ohio and southern Illinois.

A report from climate experts on Thursday said the Midwest was in the grips of the worst drought in a quarter of a century.

Nearly two-thirds of the nine-state Midwest region was in some stage of drought in the reporting week that ended July 10, up from just over 50 percent a week earlier, according to the Drought Monitor, a weekly report on drought throughout the country compiled by U.S. climate experts.

One-third of the region was in severe to exceptional drought, up from about a quarter of the region a week earlier, it said.

Corn, soybean and wheat futures prices were sharply higher again on Monday as the drought spread further.

A weekly government report on the condition of U.S. field crops is expected to show further deterioration in corn and soybeans as drought expands to areas of the U.S. Midwest that had so far escaped the dry conditions.

Grain analysts polled by Reuters said they expect the U.S. Department of Agriculture to shave 5 percentage points off the portion of the corn and soy crops rated in good to excellent condition.

The relentless drought that is expanding through the heart of U.S. corn and soybean country continues to slash crop production prospects, with little to no relief in sight.

"Up until now the western and northwest Corn Belt had been faring better, but there was deterioration there last week and I expect more this week," said Shawn McCambridge, an analyst for Jefferies Bache.

"The drought keeps spreading, they just can't get a break," McCambridge said.