Right now the areas of concern are parts of central to south Iowa, Missouri, and southern Illinois. After getting plenty of moisture in the spring, there's still enough water in the soil profile, but most of the Corn Belt has had temperatures five to ten degrees above normal for the last month.
According to Iowa State Climatologist Harry Hillaker, though summer weather patterns tend to be persistent, it can change quickly, "Usually you think of a drought as something that takes weeks, months, seasons practically to get developing. Usually it's kind of a slow moving phenomenon. But occasionally, especially this time of the year near midsummer it suddenly goes from a benign weather pattern where things are going all right to very hot, very dry."
According to the U.S. drought monitor the southeast quarter of Iowa is abnormally dry, nearly double last week's dryness.
In the Iowa Crop Progress report, topsoil moisture statewide is 24 percent short to very short. Southeast Iowa is the driest at 63 percent short to very short, posing a problem for emerging crops. Subsoil moisture is a little better, statewide it's 14 percent short to very short, but 35 percent or more in Southeast and South Central Iowa, enough for more established crops.