* StoneX cuts Brazil soy crop estimate
* Rising dollar hangs over grain markets
* Traders await U.S. fats and oils data
CHICAGO, Jan 2 (Reuters) - U.S. soybean futures slid to their lowest level since October on the first trading day of the year as crop weather improved in Brazil, the top global supplier of the oilseed, analysts said.
A rallying dollar also weighed on agricultural markets on Tuesday as it makes U.S. farm products less attractive to importers.
Corn futures dropped to their lowest price since November, while wheat declined at the Chicago Board of Trade.
Rains in Brazil dragged down soybean futures after hot, dry weather previously hurt crops in northern growing areas and spurred analysts to lower their harvest forecasts. Agribusiness consultancy StoneX cut its estimate for Brazil's crop to 152.8 million metric ton from 161.9 million tons.
"We did get improvement in weather," said Don Roose, president of brokerage U.S. Commodities in Iowa.
"These dry areas shrunk. The forecast looks like we have more normalized weather for the next 10 days or so."
Traders are also monitoring crop weather in Argentina, where farmers made good progress sowing soybeans and corn following recent abundant rainfall.
The most-active soybean contract had sunk 25-1/4 cents to $12.72-3/4 a bushel by 11:40 a.m. CST (1740 GMT) at the CBOT and touched its lowest price since Oct. 12.
Corn was down 8-1/2 cents at $4.62-3/4 per bushel and hit its lowest level since Nov. 27. Wheat lost 16 cents to $6.12 per bushel.
A monthly U.S. fats and oils report, due from the U.S. Department of Agriculture at 2 p.m. CST (2000 GMT), is expected to show the U.S. soybean crush eased slightly to 5.991 million short tons in November, or 199.7 million bushels.
Traders also continue to monitor trade disruptions in the Red Sea as container ships avoid the route that gives access to the Suez Canal, following a weekend attack on one of Maersk's vessels. (Reporting by Tom Polansek in Chicago Editing by Mark Potter)
