After an April that brought record rainfall to much of Indiana and Ohio, climatologists agree the weather pattern is improving — a welcome change for farmers in both states.

La Niña is the weather pattern keeping much of the Midwest wet. It occurs when the surface temperature of vast areas of the Pacific Ocean are cooler by at least 1 degree Fahrenheit, said Ken Scheeringa, associate state climatologist for the Indiana State Climate Office, based at Purdue.

"The La Niña that began last summer is now weakening and is expected to disappear by the end of June," he said. "However, impacts of La Nina will continue over Indiana and Ohio as long as into August because of the natural 2-3 months lag time for the atmosphere to respond to ocean temperature changes."

While La Niña's effects will linger, Scheeringa said the weather will continuously improve to more favorable planting conditions as the month of May continues.

"Farmers will get to plant their crops," Scheeringa said. "As La Niña slowly dies out, the opportunities for growers to get into their fields are coming — especially as May progresses. So, even though the situation seems desperate now, particularly in southern Indiana where some fields are still submerged, it will improve."

As the weather improves, improvement in soil condition will vary widely from field to field, Purdue Extension agronomist Tony Vyn said.

"In addition to rainfall totals and other weather conditions, there are many factors that determine soil drying rate," Vyn said. "Soil type, drainage, residue cover quantity and distribution, prior tillage operations, how level or rough the soil surface is, crop rotation and duration of ponding all play a role.

"For some farmers, soil conditions could be ready for planting a matter of days after the rains stop, but for others it could be longer than a week - even with no additional rain."

With a consecutive 7-10 day period of no rainfall, Vyn said corn farmers could have more than 50 percent of acreage planted by May 16.