CHICAGO (Dow Jones)--Corn futures on the Chicago Board of Trade rallied Tuesday, with weakness in the dollar and weather concerns attracting speculative buyers.

December corn ended up 9 3/4 cents at $3.25 3/4 per bushel, and March corn ended 9 3/4 cents higher at $3.39 per bushel. In pit trades, speculative fund buying was estimated at 7,000 lots.

The drop in the dollar provided the initial boost to prices, with midday private weather forecasts raising the threat of cooler temperatures serving as the fundamental spark to cement the market's recovery bounce, analysts said.

Late maturing corn crops remain at risk of yield losses in the event of a frost in the Midwest before October, and that provided enough concern for the market to add some premium back into prices, analysts said.

The weather and maturity of corn crops fueled some more concern in the market. U.S. Department of Agriculture said Monday 21% of the crop was reported mature, down from the five-year average of 55%. "The question is: Do we have enough time for the crop to finish, before weather shuts plants down?" said Gavin Maguire, director of research at eHedger in Chicago.

Technically inspired buying was featured as well, with oversold conditions following a week-long downtrend uncovering speculative short covering. The ability of the most-active December contract to eclipse near-term upside chart resistance coupled with borrowed strength from outside markets uncovered pre-placed buy orders to push values to session highs on the close.

Meanwhile, the T-storm Weather forecast said rain affects the central U.S. at times through Saturday. After rain ends this weekend, a cooler pattern affects the Corn Belt.

"While the newest GFS weather model is colder, frostier for Tuesday and/or Wednesday mornings of next week, many unresolved issues exist, and we feel it is best to keep highest frost chances further to the north," T-storm Weather said in the forecast.

CBOT oat futures closed slightly firmer. December oats rose one cent to $2.13 a bushel, and May oats rose one cent to $2.35.

Ethanol futures ended in positive territory. November ethanol closed up 2.3 cents at $1.624 a gallon, and December ethanol jumped 1.8 cents to $1.618.

-By Andrew Johnson Jr., Dow Jones Newswires; 312-347-4604;