(Recasts, updates with U.S. trading, adds new analyst quote, changes byline, dateline; previous PARIS/SINGAPORE)

CHICAGO, Oct 20 (Reuters) - U.S. corn and soybean futures rose on Tuesday on strong export demand while wheat firmed on concerns that dry weather could limit global production, traders said.

Soybean futures notched the biggest gains, with traders shrugging off some much-needed rain in Brazil due to the strong pace of overseas buying.

"The grains are green once again this morning, not far off highs across the board, with the same global issues overhanging the market despite a rapid U.S. harvest and increasing South American precipitation," Matt Zeller, director of market information at StoneX, said in a note.

At 10:38 a.m. CDT (1538 GMT), CBOT November soybean futures were up 7 cents at $10.61-1/2 a bushel.

CBOT December corn was up 1-1/2 cents at $4.06-3/4 a bushel.

The U.S. Agriculture Department on Tuesday morning said that private exporters reported the sale of 132,000 tonnes of soybeans to unknown destinations for delivery in the 2020/21 marketing year. It was the sixth day in a row the USDA has reported a so-called flash sale of either corn or soybeans.

CBOT December soft red winter wheat was up 2 cents at $6.29 a bushel, on track for its fifth straight day of gains.

Wheat prices peaked at $6.38-1/4, the highest on a continuous basis for the most-active contract since Dec. 24, 2014, early in the session.

Some rain has reached parched U.S. and Russian wheat belts in recent days, but weather forecasts showed little further moisture for some zones during the rest of October as farmers try to complete sowing of winter wheat.

"There could be more upside potential for wheat prices if we see more dryness in Russia and the U.S. winter wheat growing areas," said one Singapore-based trader. (Additoinal reporting by Gus Trompiz in Paris and Naveen Thukral in Singapore; Editing by Marguerita Choy)