* Light showers, moderating temperatures for United States
* Weather shift to slow crop deterioration
* Corn already damaged, some late soy to benefit
By Sam Nelson
CHICAGO, Aug 13 (Reuters) - Light showers and cooler temperatures forecast for the next week will bring welcome relief to drought-stressed corn and soybean crops in the U.S. Midwest but serious damage has already been done to crops, an agricultural meteorologist said on Monday.
"It's an improvement and will probably slow deterioration but I don't see any huge improvement either," said John Dee, meteorologist for Global Weather Monitoring.
Dee said from 0.20 inch to 0.60 inch of rain with isolated heavier amounts fell over the weekend in Minnesota, Iowa, Wisconsin and Illinois. Similar rainfall is expected on Monday in Michigan, Indiana and Ohio and from late Wednesday into Friday about 85 percent of the Midwest can expect from 0.30 inch to 0.80 inch of rain.
"Temperatures will be more comfortable with highs in the 80s (degrees Fahrenheit) in the north and the low 90s F in the south," Dee said.
Dee and other crop experts said the U.S. corn crop was already harmed beyond by the summer's heat but some of the late planted soy may be helped. "It will allow some of the filling or pod setting soybeans to develop but the damage has been done to the corn crop," he said.
Commodity Weather Group (CWG) on Monday said nearly one-third of the Midwest soybean crop remained under stress from lack of moisture and the soybean area stressed by drought may expand slightly over the next 10 days.
Parts of central Illinois, Missouri, Nebraska, western Iowa, southern Wisconsin, southwestern Minnesota and southern South Dakota will be most prone to stress, CWG said.
Also, nearly half of the Delta in the lower Mississippi crop region remains unfavorably dry for late growth in dryland areas, but rains are expected to expand from late this week into late August and will ease moisture deficits, according to CWG.
As the worst drought in over a half century took its toll, investors went on a buying spree, boosting corn prices by more than 50 percent from late May to record highs above $8 per bushel. The U.S. government on Friday released fresh crop data showing deep cuts for this year's corn and oilseed output as the drought spread through America's breadbasket.
Now, an early autumn cool down is coming following the summer of relentless heat that brought almost daily 100 F-plus readings to much of the crop belt and harming everything from corn to cattle.
The U.S. Department of Agriculture (USDA) on Friday released a shocking report showing just how bad the corn and soybean crops have been hurt during the historic drought that some were beginning to compare with the dust bowl days of the 1930's.
USDA said this year's corn crop would fall below 11.0 billion bushels for the first time in six years and the number of bushels yielded per acre was a 17-year low. Soybean production was forecast at a five year low and soy yield per acre nearly a 10-year low.
The sharp cuts in crop output even filtered into the precious metals markets, boosting gold as worries about higher food prices enhanced its allure as an inflation hedge.
Analysts and crop experts said further cuts may be seen in future reports.
Reporting By Sam Nelson; Editing by Alden Bentley