Dangerous temperatures will persist across parts of the U.S. through July, and in some areas, there's an unexpected contributor.

The phenomenon known as “corn sweat” plays a huge role in dew points across the Corn Belt during heat waves. Through a process known as evapotranspiration, the corn crop releases water from the soil and plant itself into the atmosphere. This adds moisture into the air, leading to the dew point rising.

The heat wave baking the central United States this week may feel worse than those earlier in the summer, and corn is partly to blame, forecasters say.