An arctic blast hitting the heart of the US Midwest soft red winter wheat belt this week will put 10 to 15 percent of the dormant crop at risk of winterkill damage, agricultural meteorologists said on Tuesday. While most of the northern Midwest wheat crop is protected by snow from frigid temperatures there is a strip across the central United States, from northern Missouri to central Illinois, central Indiana and parts of Ohio, that missed the recent snowfall, leaving dormant wheat exposed to winterkill. On Tuesday, morning lows dipped below 0 degrees Fahrenheit (-18 Celsius) in southern Illinois, southern Indiana and parts of Ohio, big SRW wheat country, with more chilly temperatures on the way, meteorologists said. "For the next two or three mornings, through Friday, there is going to be threats of zero to -10 (F) below readings in those winter wheat areas," said meteorologist Dan Hicks of Freese-Notis Weather in Iowa. Unprotected wheat can experience winterkill if temperatures dip below zero for four hours or more, preventing the crop from reaching its full yield potential this summer.