* USDA expected to up U.S. wheat, soy crop estimates

* Weather good for U.S. corn and soybean crops

* Chinese holidays could cut buying in U.S.

HAMBURG, Sept 28 (Reuters) - Chicago wheat and corn prices fell on Monday while soybeans prices were little changed in cautious trade ahead of new estimates of U.S. harvests from the U.S. Department of Agriculture (USDA) later this week.

The dollar's rise to around 2-month highs weighed on the market as a stronger dollar makes U.S. exports more expensive in global markets. Chinese holidays were also expected to cut buying of U.S. soybeans and corn.

Chicago Board of Trade most-active corn fell 0.6% to $3.62-3/4 a bushel at 1042 GMT, wheat was 0.6% down at $5.41 a bushel. Soybeans edged up 0.05% to $10.03 a bushel.

U.S. harvesting of corn and soybeans is speeding up and the U.S. Department of Agriculture (USDA) gives its latest forecast of wheat, soybean and corn crops on Wednesday along with inventory estimates.

Analysts expect the USDA to raise its forecasts of wheat and soybean crops. But its corn harvest estimate could be little changed.

"U.S. crop weather is looking fine with rapid progress expected to be made with U.S. soybean and corn harvests," said Matt Ammermann, StoneX commodity risk manager. "The market is not factoring in additional fear today on this score."

"There is also risk off mood ahead of the USDA’s crop and stocks reports on Wednesday. This report in September can make waves in the market although surprises are not expected this time."

Less buying by China of U.S. soybeans and corn is expected this week after hefty purchases in September.

"China is now entering a holiday period so it may well be that Chinese buying in the United States will be reduced this week," Ammermann said. "Soybeans are struggling to hold the $10 a bushel level."

Markets are also getting concerned about another wave of COVID-19 in the United States and elsewhere with renewed threats of economic damage from lockdowns, Ammermann added. (Reporting by Michael Hogan, additional reporting by Naveen Thukral, editing by Emelia Sithole-Matarise)