CHICAGO, Dec 24 (Reuters) - Spot basis bids for soybeans and corn shipped by barge to U.S. Gulf Coast export terminals were mostly steady on Tuesday, traders said.

* Crop weather in Brazil, the world's biggest soybean exporter, looks nearly ideal, fueling expectations for a record harvest there, traders said.

* Brazil competes with the United States for soy export sales to China and other importers.

* Frequent rain will mostly benefit soy and corn crop yields in northern Brazil over the next two weeks, Commodity Weather Group said.

* In Argentina, another soy and corn exporter, dryness threatens a portion of the nation's grain belt, traders said.

* CIF soybean Gulf barges loaded in December were bid at 86 cents over Chicago Board of Trade January futures, unchanged from Tuesday.

* FOB export premiums for January soybean shipments were unchanged at about 108 cents over futures.

* CIF corn barges loaded in December were bid flat at 68 cents over CBOT March corn futures.

* FOB offers for corn shipped from the Gulf in January were unchanged at 86 cents over CBOT March futures.

* Chicago Board of Trade soy and corn futures finished higher. The market will be closed on Wednesday for Christmas.

(Reporting by Tom Polansek; Editing by Mark Porter)

((Thomas.Polansek@thomsonreuters.com))

((For displays of CIF basis, click on the codes in brackets:

U.S. CIF Gulf soybeans

U.S. CIF Gulf corn

U.S. CIF Gulf SRW wheat

U.S. CIF Gulf HRW wheat For displays of FOB basis, please click on the following codes in brackets:

U.S. FOB Gulf corn

U.S. FOB Gulf soybeans

U.S. FOB Gulf SRW wheat

U.S. FOB Gulf HRW wheat

LINKS Corn prices page: cpurl://apps.cp./cms/?pageid=corn-cash-market Wheat prices page: cpurl://apps.cp./cms/?pageid=wheat-cash-market U.S. barge freight U.S. export sales estimates U.S. grain export summary Brazil soybean export prices Brazil corn export prices Argentina grain prices Russia grain prices ))