United States

By Alex Sosnowski, Expert Senior Meteorologist

July 13, 2012; 6:08 AM

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Heat and drought threaten to take their toll on the northern part of the corn belt in the coming weeks.

The ongoing Midwest drought has the potential to have the greatest impact since 1988.

Spotty rain will fall on part of the Ohio Valley states over the next week. However, much of the corn crop in this area has already been toasted by drought and heat thus far.

The impact of heat and drought is likely to spread into more of the Midwest through the weekend.

Just like areas farther south in corn country in the Midwest during late June and early July, the building heat, combined with diminishing rainfall, could affect the maturity and eventual production of the crop farther northwest.

RELATED: Photos Capture Corn Devastation in Dry Midwest

High pressure, responsible for the heat to begin with, in the Midwest migrated to the West this week. However, it appears this high will rebuild eastward this weekend into next week.

Iowa has been a leader in United States corn production over the past couple of decades.

According to the United States Department of Agriculture (USDA), Iowa has now joined the list of corn-producing states in declining progress of the crop this season.

Heat and drought hit Iowa hard during the critical corn pollination period in recent weeks. Much of Iowa has had less than than 25 percent of their normal rainfall since late June, combined with 100-degree temperatures.

In more northerly states, such as portions of Minnesota, Nebraska and South Dakota, where pollination was more successful with more moist conditions and less extreme temperatures, a new wave of heat without sufficient rain threatens to stunt maturity of the corn and limit production later.

Homegrown heat continued over much of the region this week, despite a push of air from Canada. The air merely replaced 100-degree temperatures with 90-degree temperatures, low humidity and cooler nights.

Essentially areas near and west of the Mississippi River in the region will see a return of 100-degree temperatures, higher humidity, warmer nights and little or no rainfall moving into next week as the upper-level high pressure area returns from its trip to the West.

Seed companies claim that compared to 1988, corn varieties are more drought resistant. Unfortunately, even drought-resistant corn needs some rain and a break from the heat to recover.

While many more acres of corn has been planted this year, compared to 1988, yields will be below original expectations due to crop failures already in the Ohio Valley states and lower production and potential failures farther northwest.

In addition to corn, soybeans are a major crop in the region and could be the next to become a casualty of the building heat and drought if conditions do not significantly change.