Recent concerns over insufficient corn and soybean supplies for 2011 could intensify if Midwest weather proves unfavorable for corn and soybean production this spring or summer. Yet, the current La Niña weather system that has prevailed since April 2010, is likely to pose little threat to Midwestern corn and soybean yields this year, according to Harry Hillaker, Iowa state climatologist.

“The impact from a La Niña weather system on crop production in the Midwest varies quite a bit depending on their timing and how long they last,” says Hillaker. “This La Niña is very different than the one during 1988 that everyone thinks about as being associated with severe drought conditions.”

Cool Pacific water temperatures off the Peru coast dictate La Niña weather conditions that can impact temperature and rainfall patterns in many parts of the globe. “The current La Niña is likely to begin fading as we head into spring, and historically fading La Niña events have given no consistent signal for the type of Midwest growing season weather to expect,” says Hillaker. “Yet, there is a hint of a tendency for such events to favor a warmer- and drier-than-usual growing season for us.”

Still, the current La Niñhas some similarities with another one that occurred only a few years ago, he adds. “The 2007-2008 La Niña is the most recent corollary to the La Niña we’re seeing now,” says Hillaker. “In 2008, Iowa had a ridiculously wet, late spring and early summer, which caused a lot of flooding issues. However, the rest of that year was fairly favorable for crop production.”

This year, Iowa and the northern Midwest states will likely be going into spring with plenty of subsoil moisture again, Hillaker points out. “The northern Corn Belt states have been really wet and snowy this fall and winter, in sharp contrast to the eastern Corn Belt and states west and south of Iowa, like Nebraska, Kansas and Missouri,” he says. “For Iowa, we’ve had four very wet years in a row, from 2007 to 2010; so, even a normal growing season would be quite a change for us.”

The current weather outlook for Iowa is that March will slightly favor cooler-than-normal weather and April will have stronger odds for wetter and warmer-than-normal weather, says Hillaker. “For the summer, we will likely see one unusually warm month,” he adds. “Yet, there are no strong tendencies for the summer as a whole.”