Since 2011 UNL has been running a computer model to project corn yields inseason. This is the first run of 2014, based off weather data as of July 20. More information at the link: http://cropwatch.unl.edu/archive/-/asset_publisher/VHeSpfv0Agju/con...

Now, the weather since July 20 has not been ideal, but let's not kill the Nebraska dryland crop just yet.

From the article:  
In general, when comparing the median estimated yield for 2014 to the long-term average yield potential based on 25+ years of weather data, 2014 irrigated yields are near-average in Nebraska and Wisconsin and trending higher than the long-term yields in Kansas (Table 1). In fact, there is already a high probability of above-average irrigated yield in Kansas due to below-average temperature so far this season. In the case of irrigated corn in Nebraska, forecasts indicate a median yield potential 5-6 bushels per acre below the long-term average at North Platte and Holdrege. However, this is not consistent throughout the state; estimates of irrigated corn yield potential are near-average at Mead or even above the long-term average at Clay Center and in northern Nebraska (Concord and O'Neill).

In the case of dryland corn, above-normal rainfall, coupled with low rates of daily water use due to low daytime temperature, are the leading factors contributing to the above-average yield potential forecasts across the entire Corn Belt (Tables 1 and 2) . Remarkably, there is already a high chance of above-average dryland yields in eastern Nebraska (Mead and Concord), Kansas, and almost all simulated locations in the central and eastern Corn Belt (Iowa, Illinois, and Ohio). In Wisconsin, where the growing season is shorter than in the other simulated locations, the median dryland yield was near the long-term average because the positive effect of above-normal rainfall was offset by the negative impact of late sowing in 2014 (about 10 days later than an average year) and the higher probability of an early killing frost during grain filling. In the case of dryland corn in Nebraska, the model is estimating yields of +14 (Clay Center), +45 (Mead), and +36 (Concord) bushels per acre above the long-term average dryland yield potential for each location.

Factors in 2014 that may cause lower yields than these forecasts, even with optimal management, include hail or flood damage as well as a greater likehood of foliar diseases. Likewise, given the large amount of rain in some areas, nitrogen leaching and/or denitrification may limit yields due to nitrogen deficiency if additional nitrogen was not applied to affected areas.