Ag Weather Forum

Limited Central US Rain Ahead

Bryce Anderson
By  Bryce Anderson , Ag Meteorologist Emeritus
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Showers will be light and limited over northern and central crop areas going into the final week of August. (DTN graphic)

Crop ratings declined during the past week, although not as much as the commodity trade expected. The corn good-to-excellent rating total of 69% was 2 percentage points below a week ago. Iowa saw an extensive decline of 10 points in the good-to-excellent total to 59%. That lower total was no surprise due to the derecho on Aug. 10. The Iowa soybean crop fell by 8 points in the good-to-excellent total. Meanwhile, the expansion of dryness and drought across the central United States showed in a decline in Nebraska corn and soybean ratings by 5 percentage points in good-to-excellent totals for both crops.

Otherwise, mostly favorable conditions were noted across the country during the last week. The derecho had less damage over Illinois, Wisconsin, and Indiana than in Iowa and brought some decent rainfall to boot. A frontal passage over the weekend also provided some scattered showers over the far northern and south Midwest, maintaining overall favorable conditions for filling corn and soybeans. Scattered showers fell in drier portions of the Delta and Southeast, boosting moisture supplies for filling soybeans and cotton. West Texas and the surrounding area were not as fortunate with showers and heat built into the region for the week. Several days above 100 degrees Fahrenheit increased irrigation demand across the region, but with bolls starting to open in the region, rainfall will become less of a concern. Crop ratings did not respond to the heat, actually falling 2 percentage points in the poor-to-very poor categories.

A week of mainly light rain is indicated for many crop areas. With a ridge of high pressure anchored in the Four Corners region and troughs mostly staying north into Canada, very little precipitation is expected through the next week across the major growing regions. The northern storm path will keep periods of showers going near the U.S.-Canadian border, but will be isolated. This should benefit the ongoing spring wheat harvest, as the region will be mostly dry with intermittent showers to work around. A weakness in the ridge will also continue periods of showers over the next week in the western Plains and Southeast, benefiting immature corn and cotton, respectively.

But the overall drier pattern will stress filling corn and soybeans in the heart of the country. Midwest soil moisture was adequate going into August in many areas, but is declining under these conditions and is less than ideal for the filling crops. Places that are already dry, especially for Iowa and northeast Nebraska, where drought conditions have been persistent over the last month, will likely see continued decline in crop ratings along with earlier maturity and lower crop quality.

The tropics are also starting to get more active again. A couple of tropical waves are taking the long path from Africa toward North America. One of these waves has entered the Caribbean and could move into the Gulf of Mexico over the weekend, and another is starting to form into a tropical storm in the central Atlantic. This would not be a factor for the mainland U.S. until the early or middle portions of next week. However, both of these systems should be watched for impacts near the Gulf Coast.

John Baranick can be reached at


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