An increase of just one degree in the average nighttime temperature during grain fill can cost an Illinois corn grower 3.6 bu. per acre, according to a recent study by The Climate Corporation. Its newly released Outlook Report quantifies the historical impact of nighttime heat stress on length of grain fill period and corn yield.

“Growers and agronomists have known for some time that higher nighttime temperatures lead to shorter grain fill periods and generally lower yields,” says Jeff Hamlin, director of agronomic research at The Climate Corporation, “but until now, very few analyses have quantified the impacts of higher nighttime temperatures, and this insight will help growers adjust their yield expectations more accurately as the season progresses.”

The Climate Corporation analyzed 20 years of weather and yield data from Indiana and Illinois using its powerful weather data platform. Key conclusions from the outlook report include:

Over the last 20 years, Illinois corn growers have seen the length of the grain fill period decrease by one week for every 2.6 degree Fahrenheit increase in average temperatures during grain fill, while Indiana corn growers have seen the length of the grain fill period decrease by one week for every 2.8 degree Fahrenheit increase in average nighttime temperatures during grain fill.

Over the last 20 years, Illinois corn growers have seen yields decrease by an average of 3.6 bu. per acre for every one degree Fahrenheit increase in average nighttime temperatures during grain fill. In Indiana, the drop in yield has averaged 2 bu. per acre for every one degree Fahrenheit increase in average nighttime temperatures during grain fill.

To access the Outlook Report, visit http://climate.com/2012Outlook/nighttime-heat-stress.