Prices for corn and soybeans hit all-time highs Thursday as questions built about the extent of damage to the crops from the merciless summer heat.

Corn for September delivery rose 12.75 cents to finish at $8.0775 per bushel, besting its all-time high of $7.87 per bushel set in June 2011. August soybeans gained 50.25 cents, or 3 percent, to end at $17.3375 for a second straight second record-setting day.