The new Yield Forecast came out from the UNL project on today. There is a high probability of near- or above-average yields at all six Iowa locations with 95% probability being near- or above average at all locations except northwest and north central Iowa. The range of yield potentials forecast is still large due to only being roughly halfway through grain fill.
Probability of an early-killing frost is likely (>50%) in in northern IA locations. It is very likely that maturity will be reached in central and southern Iowa before a killing frost.
As grain filling progresses and observed weather data become available, the range of forecasted yields will continue to narrow. It should be noted that this forecast does not take into consideration stand establishment issues, hail, flooding, replant situations, disease/insect incidence, or nitrate leaching. Additional yield forecast information from Iowa and the other 9 states can be found at; https://cropwatch.unl.edu/hybrid-maize-aug-14-yield-forecasts.