MILWAUKEE – Chef Dan Jacobs expected his recent batch of jalapeño poppers to be tame because peppers grown at this time of the year are generally mild. But he quickly discovered that his spicy appetizer carried an unexpected fire.

"Wow, those things are no joke. They are hot," said Jacobs, the top chef at Roots Restaurant and Cellar in Milwaukee. "At this time of year, they shouldn't be this hot. But the warm weather, the no rain, that's going to cause that."

Temperatures above 100 degrees and droughtlike conditions have baked parts of the upper Midwest for weeks, taking a severe toll on corn and soybeans. But the heat brought an expected benefit for peppers and other crops: Their flavors became unusually concentrated, producing some of the most potent-tasting produce in years.