Cooler forecasts expected after the hot weather, over the next 10 days, along with some rain helped ease fears about late-planted crops facing heat-related stress, however.
Markets had been down since the US Department of Agriculture (USDA) released its weekly crop condition report on Monday. Although corn saw a slight increase in good to excellent ratings, the warm weather at the beginning of the week caused traders to move with caution.
"After a slight improvement of the crop's condition published earlier this week by the USDA, the new heatwave expected on the Corn Belt has pushed the forecasted rains into the background," consultancy Agritel said in a note.
The USDA surprised traders by raising its condition rating for US corn to 58pc good-to-excellent in a weekly report. That was up from 57pc a week earlier and above market expectations for 56pc.
US soybeans were rated 54pc good-to-excellent, up from 53pc last week and above analysts' expectations for 53pc.
Traders were still monitoring heat, with temperatures set to exceed 90 degrees Fahrenheit (32°C) in much of the Midwest in the coming days before easing.
"There's just uncertainty," said Joe Aiello, senior agriculture adviser with Roach Agriculture Marketing. He added that until the USDA releases its revised acreage report on Aug. 12th, the weekly crop progress reports may not have as much impact as they normally do.
The September corn futures contract on the Chicago Board Of Trade (CBOT) was up 3-1/4 cents, or 0.7pc at $4.38-1/2 bushel by 11:15 a.m. (1615 GMT).
Corn prices hit a five-year high of $4.64-3/4 on Monday amid concerns that hot, dry weather could further hamper crops that already endured poor planting conditions due to torrential spring rain.
CBOT August soybeans were up 1-1/2 cents, or 0.2pc at $8.89-1/4 a bushel, after also recovering from a small earlier fall.
CBOT September was up 1/4 a cent, or 0.1pc to $5.07-3/4 a bushel.
"Wheat is really just a follower at this point," said Aiello. "There is an abundance mixed with nicer weather in Russia and the Black Sea region that won't damage crops."
Egypt's state grain buyer, the General Authority for Supply Commodities (GASC), said it bought 60,000 tonnes of Russian wheat in a tender on Wednesday.
As in recent Egyptian tenders, wheat from Black Sea suppliers Ukraine, Russia and Romania dominated the bidding, with no US or western European wheat offered.