CHICAGO, Nov 23 (Reuters) - U.S. soybean futures climbed to $12 a bushel on Monday for the first time in four years, buoyed by worries about dry conditions in parts of Brazil and Argentina that stoked supply concerns, analysts said.

Corn advanced, also lifted by worries about dryness in South America, and wheat futures followed the firm trend.

As of 1:05 p.m. CST (1905 GMT), Chicago Board of Trade January soybean futures were up 12-1/2 cents at $11.93-1/2 per bushel after touching $12 in opening moves, the highest price for a most-active soybean futures contract since June 2016.

CBOT March corn was up 4 cents at $4.32-1/4 a bushel and March wheat was up 4-1/2 cents at $6.04 a bushel.

Weekend rains were limited to far northern areas of Brazil's soy belt, space technology company Maxar said in a crop weather note, and forecasts for this week were not much better.

"Rainfall amounts are expected to be light in most areas, which will maintain dryness concerns across most of Brazil, stressing corn and soybeans," the Maxar note said.

Brazil is the world's top soybean exporter and Argentina is No. 3 after the United States.

The Chicago soybean futures forward curve shows prices have jumped for all contracts through to the middle of next year.

Corn futures drew additional support from export demand. The U.S. Department of Agriculture confirmed private sales of 334,000 tonnes of U.S. corn to unknown destinations, the latest in a series of daily corn sales announcements.

"Corn is also firm on poor South American crop weather, including in Argentina, with more export demand also expected, with U.S. corn looking the cheapest in the world," said Matt Ammermann, StoneX commodity risk manager.

CBOT wheat futures followed the strength in corn and soybeans, but gains in K.C. hard red winter wheat were capped by weekend rains that bolstered crop prospects in parts of Kansas and Oklahoma, two of the top U.S. producers of the grain.

"K.C. wheat might be reflecting a little of moisture that they saw yesterday in Kansas," said Tom Fritz, a partner with EFG Group in Chicago.

(Additional reporting by Michael Hogan in Hamburg and Naveen Thukral in Singapore; Editing by Mark Heinrich and Barbara Lewis)