GRAINS-U.S. corn price jumps 2.7 pct on U.S. weather worries

* Corn jumps on U.S. weather concern

* Wheat firms on fears of high-quality shortage

* Soybeans up as U.S. crop condition declines

(Updates with European trading, adds new comment) HAMBURG, July 18 (Reuters) - U.S. corn prices were up 2.7 percent on Tuesday as concern about hot, dry weather in U.S. grain belts stoked fears of crop damage. Wheat gained 1.7 percent and soybeans rose 1.3 percent after the U.S. Department of Agriculture (USDA) said the condition of both U.S. crops had deteriorated in the last week as unfavourable weather continued. "Corn, wheat and soybeans are rising today because of concern about the declining condition of U.S. crops and worry about U.S. weather forecasts, with corn providing the main impetus," said Matt Ammermann, commodity risk manager at INTL FCStone.

The Chicago Board of Trade's December corn contract, the most active,

was up 2.7 percent at $3.98-3/4 a bushel at 1055 GMT. Corn closed down 0.1 percent on Monday.

September wheat rose 1.7 percent to $5.14-3/4 a bushel, having closed down 0.9 percent previously. November soybeans rose 1.3 percent to

$10.10-3/4 a bushel. "The weather outlook for the coming week is pointing toward above average temperatures for the U.S. corn belt," said Angus Thornton, commodity analyst at Profarmer. The weather outlook threatens further downgrades to the quality of U.S. crops. "The USDA crop condition report on Monday assessed 64 percent of U.S. corn in good to excellent state, down from 65 percent a week ago," Ammermann said. "A decline of this scale had been anticipated but corn condition is starting to look a lot worse than this time last year when 76 percent of the U.S. corn was rated good to excellent." "In the next two weeks U.S. corn regions need widespread rains. But forecasts remain for generally hot weather with extensive rain not expected." "The market is now expecting the USDA to reduce its forecast of U.S. corn yields in its August supply and demand report, the question is now how big the reduction will be." The USDA said the U.S. spring wheat crop was 34 percent good-to-excellent, down from 35 percent a week ago and down from 69 percent last year. "Wheat remains supported by concern about shortages of high protein supplies following expected heat stress to the U.S. spring wheat crop. U.S. spring wheat conditions were also down on Monday," Ammermann said. "The big panic in the wheat market seems to be over but there is continued steady upwards momentum because of the protein and quality issue, although a large Black Sea region harvest is limiting upward movement." The USDA said U.S. soybeans were 61 percent good-to-excellent, down from 62 percent last week.

(Reporting by Michael Hogan and Colin Packham; Editing by Greg Mahlich)