CHICAGO, Sept 29 (Reuters) - U.S. corn futures rose on Wednesday, rebounding from declines a day earlier, as traders adjusted positions ahead of a key quarterly stocks report from the U.S. government, analysts said.

Soybeans and wheat futures also advanced, with all three commodities bucking pressure from a sharply higher U.S. dollar.

Chicago Board of Trade December corn settled up 6-1/2 cents at $5.39 per bushel, but stayed inside of Tuesday's trading range.

CBOT November soybeans ended up 6-3/4 cents at $12.83-3/4 a bushel and December wheat rose 3-3/4 cents to settle at $7.10-1/4 a bushel.

Corn futures rose ahead of Thursday's quarterly stocks report from the U.S. Department of Agriculture (USDA). Among analysts surveyed by Reuters, the average estimate of U.S. Sept. 1 corn stocks was at 1.155 billion bushels, which is down from the 1.187 billion bushels that the USDA projected in its last monthly supply/demand report.

"Corn stocks are expected to be lower, and they could be (down) more than that, based on how the cash market is here. The interior markets are very strong," said Jack Scoville, analyst with the Price Futures Group in Chicago.

CBOT soybeans followed corn higher, although the average analyst estimate of U.S. Sept. 1 soybean stocks, at 174 million bushels, is close to the USDA's last forecast of 175 million. Analysts noted that the USDA's quarterly stocks reports have a history of jolting markets.

Corn and soybeans drew additional support from export optimism as more U.S. Gulf terminals reopen following damage from Hurricane Ida last month. Farm cooperative CHS Inc said on Tuesday that operations were resuming at its export terminal in Myrtle Grove, Louisiana.

Wheat futures firmed on expectations that the USDA would trim its estimate of the U.S. 2021 wheat crop in a separate small grains report also due on Thursday.

In addition, benchmark wheat futures on the Paris-based Euronext market matched a life-of-contract high as an import purchase by Algeria and a further drop in the euro bolstered export prospects.

(Reporting by Julie Ingwersen in Chicago; Additional reporting by Gus Trompiz in Paris and Naveen Thukral in Singapore; Editing by Mark Potter, Uttaresh.V and Peter Cooney)