Corn plants were curling up tightly in the mid-day heat last week on Mason Hoffman’s farm in Palo Alto County, where rainfall continued to be sparse even as showers brought long-awaited relief to much of Iowa.

“Every day you’re seeing more and more spots roll up,” Hoffman said June 24. “Even the good ground is starting to show stress.”

Ninety-five miles southwest of Hoffman’s farm, a storm system rattled Shelby County farmer Sam Kenkel awake in the middle of the night. 

“It was glorious,” said Kenkel, who received a total of about 2.5 inches of rain from a couple systems last week. “We’re so thankful for getting some rain and not any of the hail that some other places did.” 

The volatile storms produced large hail that shredded crops in several locations. Some of the most severe damage...