U.S. wheat futures rose for a second session on Wednesday, underpinned by forecasts of rain in the U.S. Plains grain belt which could potentially damage crops in the key production region.

Soybeans rose on renewed worries about the impact of recent rain damage to Argentina's crop now being harvested. Corn was up on spillover support from the wheat and soybean markets.

Chicago Board of Trade most-active July wheat was up 0.5 percent to $4.66-1/2 a bushel at 0955 GMT. The July contract touched its lowest since May 12 at $4.57-3/4 a bushel on Tuesday before rebounding.

Most active July soybeans rose 0.7 percent to $10.63 a bushel and most active July corn was 0.3 percent higher at $3.98-3/4 a bushel. "We have something of a weather market today," said Frank Rijkers, agrifood economist at ABN AMRO Bank.

"Wheat is being supported by concern about rain in parts of the United States which threatens to damage the wheat crop at this stage of its growth."

Showers in the U.S. Plains winter wheat belt will diminish in the southwest during the rest of the week allowing some improvement in harvest conditions, but south eastern areas remain unfavorably wet, the Commodity Weather Group said.

The rain comes at a time when U.S. crop development has been broadly favorable.

The U.S. Department of Agriculture (USDA) rated 62 percent of the U.S. hard red winter wheat crop in good to excellent condition compared with 45 percent at this time last year, the agency said in a weekly progress report on Tuesday.

"Soybeans are being supported by concern about recent damage to Argentina's crop which could reduce its exports, especially of soymeal," Rijkers said. "Corn is being pulled up by the general market strength without specific new factors today."

"Soybeans are also seeing some short covering after recent price falls. The market is hoping for more information about the impact in the export sector of the rain damage to Argentina's harvest losses."

Argentine soybean exports could fall by as much as 25 percent this year after severe rains earlier in the year left many fields underwater, damaging oilseed quality.

In April, floods inundated key farm areas of Argentina, the world's third-biggest exporter of unprocessed soybeans and largest exporter of soymeal, prompting Argentina's Rosario grains exchange to cut its forecast for the current soybean harvest to 55 million tonnes from a previous forecast of 59 million tonnes.