CHICAGO (Dow Jones)--Chicago Board of Trade corn futures are expected to open lower Wednesday morning as harmless weather and an optimistic crop outlook keep the market under pressure.

Corn is called 1 to 2 cents lower. In overnight trade, September corn was down 1 1/4 cents to $3.11 per bushel and December corn was down 2 cents to $3.17 1/4.

Outside markets, which weighed on corn and other commodities Tuesday, are seen as a mixed influence Wednesday, but fundamentals remain bearish, traders said. The trade is continuing to closely watch weather forecasts for signs of an early frost that could hurt the late developing crop, but so far none are in sight.

The crop's late development remains a concern and has not been helped by recent cool weather. DTN Meteorlogix said the crop should be helped by "somewhat warmer temperatures" late this week into early next week.

Traders said the bearish crop expectations were highlighted by Tuesday afternoon estimates from commodity brokerage firm FCStone, which forecast the 2009-10 corn crop at 13.020 billion bushels, using an average yield of 162.7 bushels per acre.

In August, FCStone pegged the corn crop at 12.814 billion bushels, with a yield of 160 bushels per acre. The U.S. Department of Agriculture put the U.S. corn crop at 12.761 billion bushels.

The large estimate weighed in overnight trade, traders said.

The soybean market, whose recent bullishness had dragged corn higher at times, is in retreat, which could put more pressure on corn, traders said. One trader said that corn and wheat "don't have a chance" if soybeans continue to break hard.

Corn is under pressure technically, although it trimmed early losses in Tuesday's session to close right at the previous summer low in the December contract. But traders are talking about corn making a run at $3 unless a frost threat emerges soon.

The next upside price objective is to push December corn prices above solid technical resistance at last week's high of $3.37 1/2 a bushel, a technical analyst said. The next downside price objective for the bears is to push and close prices below solid technical support at the August low of $3.11 1/2 a bushel.

First resistance for December corn is seen at $3.25 and then at Tuesday's high of $3.29, the technical analyst said. First support is seen at Tuesday's low of $3.16 1/2 and then at $3.11 1/2.

There were 209 deliveries reported against the September futures contract, the first deliveries this week.

-By Ian Berry, Dow Jones Newswires; 312-341-5778; ian.berry@dowjones.com