Storm clouds started building outside while farmers, agronomists and others packed the Palo Alto County Extension office last week to figure out what to do with thousands of corn and soybean acres that haven’t been planted yet in the area.

“I’ve got 300 acres of corn left to plant,” said Scott Whaley, a Palo Alto County Farm Bureau member. He got a portion of his crop in two weeks ago, but frequent rain storms have slowed planting progress in northern Iowa compared to the rest of the state.

“The storms just seem to build right over the top of us,” said Terry Naig, who farms near Cylinder. The meeting was punctuated by the squeal of a weather...