According to Iowa State University Extension Agronomist Brian Lang the record yields this year are a pleasant surprise considering what we think we understand about weather conditions and crop production. This was not a perfect weather season to produce record yields.
There were a couple of late spring frosts to potentially affect stand and early crop development. There was warmer than normal weather during grain fill, whereas cooler than normal weather during that time should maximize yield by extending the grain fill period.
There was an incredible amount of rainfall this season (nearly 50 inches), running about twice of the long-term normal rainfall of 25 inches for the crop season.
Local farmers agree with Brian Lang adding they had a late start harvesting, due to heavy rains this summer. Farmers are experiencing highest average yields and a surprisingly good quality of crops even with those set backs.
Winneshiek County has completed the soybean harvest and the corn harvest will be finished soon.
November 9th summary of state-wide Iowa crop production posted at:
https://www.nass.usda.gov/Statistics_by_State/Iowa/Publications/Crop_Report/2016/IA_Crop_Production_11_16.pdf