CBOT July wheat settled down 8-3/4 cents, nearly 2 percent, at $4.33-1/2 per bushel, after touching $4.32-3/4, its lowest since April 28.
K.C. July hard red winter wheat ended down 5-3/4 cents at $4.44-1/4 a bushel and MGEX July spring wheat fell 9-1/2 cents at $5.44-3/4.
Ahead of the US Department of Agriculture's weekly crop progress report due later on Monday, analysts surveyed by Reuters expect the government to rate 51 percent of the US winter wheat crop as good to excellent, down from 54 percent the previous week.
Trades shrugged at better-than-expected weekly export data. The USDA reported export inspections of US wheat in the latest week at 615,029 tonnes, above a range of trade expectations for 350,000 to 600,000 tonnes.
The CBOT reported one delivery against the CBOT May wheat contract and seven K.C. wheat deliveries. There were no deliveries of MGEX May spring wheat.