South America Calling

Needed Rains Falling in South America

John Baranick
By  John Baranick , DTN Meteorologist
More rains are indicated for the main winter wheat areas in Argentina and southern Brazil. (DTN graphic)

Adding on to good rainfall from a week prior, this current week also saw some good rains across Argentina and southern Brazil as another system moved through the region. Rainfall was scattered and not heavy, but welcome to ease some of the dryness in the region.

Amounts were generally in the 10-to-25-millimeter (0.40-to-1-inch) range, but good for early spring. Developing and reproductive winter wheat benefited from the rainfall, though more will be needed, and especially to recharge soils for soybean and full-season corn planting in the next couple of weeks.

Full-season corn planting is already underway in Brazil but at a slow pace. The recent and forecast showers should help to pick that pace up a bit.

Speaking of the forecast, there is a weak system that will bring scattered showers to both Argentina and southern Brazil Sept. 5-6. Rainfall amounts are likely to be less than 10 mm (0.40 inches) for most areas, but will still be helpful. But another slow-developing system Sept. 6-9 could bring much heavier amounts. Those are indicated to come mostly to northern Argentina and Rio Grande do Sul, Brazil where up to 100 mm (4 inches) is being forecast. Southern Argentina wheat areas also look to have much better opportunities for moderate amounts over 25 mm (1 inch) as well. And the pattern looks to stay active into mid-September, at least for southern Brazil.

Argentina areas could be lacking, and producers here will hope that modeled amounts are understating the chances for good rainfall amounts as more of their wheat crop gets into reproductive stages. But the news is good for southern Brazil, which is still trying to get out of the shortened wet season and drought from the last crop year.

In central Brazil, where the wet season typically starts toward the end of September, models are not pointing to any early start this year. Going back into a La Nina pattern this spring and summer, the start of the wet season is typically delayed. That is not always the case, but it is the trend. Models are suggesting that the delay may be relatively short, on the order of a week or so, but we will have to see. Soybean planting is restricted from being planted until either Sept. 10 or 15 depending on the state so there is time for models to adjust before producers have a chance to get into their fields.

After the horrific late start of three to four weeks that occurred last year, producers would probably take a one-week delay as a blessing. La Nina still bears the risk of a shortened wet season, putting second-crop (safrinha) corn in jeopardy again this crop year, so forecasts will be closely watched to see if we end up with significant delays.

Last year's delay and quick end to the wet season left soils dry while safrinha corn went through both pollination and crop fill. The increased risk of winter frosts that also come with La Nina came in three waves as well. The combination of drought and freeze dramatically reduced yields. If there is any delay to the start of this season, you can be sure people will start to get nervous about a repeat affair in Brazil.

John Baranick can be reached at


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