* Rains boost soil moisture in dry Argentine corn, soy areas
* Most corn contracts match contract lows
* Wheat rises as dry U.S. Plains conditions put crop at risk (Recasts throughout, updates prices, adds quote, changes byline, changes dateline from SINGAPORE/PARIS)
CHICAGO, Dec 18 (Reuters) - U.S. soybean futures slumped to three-month lows on Monday as rain in Argentina eased concerns that farmers would scale back planting in the third largest soybean exporting country and largest soy product supplier.
Corn futures also declined on the rainy Argentine weather and pressure from abundant supplies of the grain. Wheat futures edged higher on concerns over dry weather hurting the U.S. winter crop.
"Near term rains in Argentina are the focus today," said Rich Nelson, chief strategist for Allendale Inc.
"The market is also responding to some reports that USDA could raise corn yields next month. Those are two very bearish short term factors," he said.
Rains that fell on Argentina's main farm belt over the weekend brought relief to parched soy and corn-growing land, meteorologists said on Monday, allowing the planting of crops to resume in most of the affected areas.
But forecasters noted that crops would need more precipitation following a very dry start to the planting season.
"The rains led to notable improvements in soil moisture, but more rainfall will still be needed to end the dry-ness in northern and central Argentina," Kyle Tapley, meteorologist with MDA Weather Services, said in a note to clients.
Chicago Board of Trade January soybeans fell 8-1/4 cents, or 0.9 percent, to $9.59 a bushel at 12:12 p.m. CST (1812 GMT), the lowest since Sept. 13.
Soybeans fell despite news of large sales to China. The U.S. Department of Agriculture on Monday reported 396,000 tonnes in sales to China after confirming 257,000 tonnes in sales to the world's top importer on Friday.
CBOT March corn fell 1/2 cent to $3.47 a bushel after earlier matching its contract low of $3.46-1/2. May through September also matched contract lows and May 2019 futures notched a new low.
Speculation that USDA may raise its U.S. corn production estimate next month weighed on prices after private analytics firm Informa Economics lifted its corn crop estimate on Friday.
CBOT March soft red winter wheat rose 2-1/4 cents to $4.20-1/2 a bushel, while K.C. March hard red winter wheat gained 2 cents to $4.19-1/2 a bushel.
A combination of delays to autumn planting and dry conditions in the southern U.S. Plains have left the hard red winter crop vulnerable to freeze damage, crop experts said, which could further tighten supplies of high-protein wheat. (Additional reporting by Sybille de La Hamaide in Paris, Naveen Thukral in Singapore; Editing by Adrian Croft and Tom Brown)