Chicago wheat futures eased for a second session on Friday, as slow U.S. exports and forecasts for more rain relief in dry growing belts stifled a wave of buying that took prices to a four-week high earlier this week.

Corn was almost unchanged and soybeans were slightly higher as investors made adjustments in the run-up to U.S. crop forecasts on Tuesday, which are being closely watched for a clearer indication of how large the ongoing corn and soy harvests are likely to be.

Continued strength in the dollar put a lid on U.S. crop futures, making them less attractive to overseas buyers, while investors were cautious ahead of monthly U.S. jobs data on Friday that could influence a Federal Reserve decision on whether to raise interest rates next month.

Chicago Board of Trade December wheat was down 0.8 percent at $5.22-1/4 a bushel by 1143 GMT. December corn edged up 0.1 percent to $3.75 a bushel while January soybeans were up 0.4 percent at $8.67-3/4 a bushel.

"Wheat and corn prices are under pressure following weak U.S. export data," said Paul Deane, senior agricultural economist at ANZ Bank. "The stronger U.S. dollar is likely to hurt export volumes in the medium-term and will weigh on commodity prices."

The U.S. Department of Agriculture (USDA) on Thursday reported wheat export sales for 2015/16 in the week to Oct. 29 at 84,600 tonnes, below a range of trade estimates for 300,000 to 500,000 tonnes and the lowest weekly total since Sept. 24.

The sluggish exports, along with forecasts calling for more beneficial rainfall in parts of the U.S. wheat belt, helped stall a rally that analysts said had been fueled by short-covering by investment funds and by an unusual premium for Chicago wheat.

"Chicago December is now at a 40 cent premium to Kansas December. Clearly this is an issue with near-term supply of U.S. soft red winter wheat," director of agricultural strategy at Commonwealth Bank of Australia, said in a note.

The current premium for Chicago futures, which usually trades at a discount to the higher-protein hard wheat traded in Kansas futures, reflects a rain-hit U.S. soft wheat harvest. The corn and soybean markets were increasingly focused on next Tuesday's USDA monthly crop report, which is expected to raise production estimates for this year's U.S. harvest.

Rising yield expectations and lower export sales this week contributed to a sharp drop in corn and soybean futures on Thursday, before they steadied in Friday trade.