South America Calling

Lagging South America Rainfall

John Baranick
By  John Baranick , DTN Meteorologist
Rainfall during the last 30 days is well-below normal over much of the South American continent. (DTN graphic)

The central Brazil wet season arrived approximately two weeks behind normal. According to USDA Chief Meteorologist Mark Brusberg, the wet season, when central Brazil receives its first 30 millimeters (1.2 inches) of rainfall, typically begins on Sept. 26. There is some decent variability in this start date, and La Nina years typically have produced a delayed start to the season. This year followed suit as Mato Grosso, the region's most productive state for soybeans, received its first 30 mm on Oct. 11-12.

Scattered showers have followed every day since through central Brazil. Model estimates of 50 to 100 mm (about 2 to 4 inches) have fallen in central Brazil, including Mato Grosso, since that time. However, that has not been able to make up for deficits during the prior two-week dry period and estimates over the last 30 days are well-below normal.

In central Brazil, rainfall estimates have been a meager 20 to 40% of normal over the last 30 days in areas where the scattered showers have been more isolated than persistent. This is likely producing areas of good planting and early growth where the showers have been more in line with normal, and areas of continued dryness and stress. The overall combined effect is still negative for corn and soybean production in the heart of the country.

The good news for producers in Brazil is that forecasts are for the scattered showers to continue during the next 10 days. Some of the areas least affected during the last two weeks may turn out to have more favorable conditions going forward.

Further to the south, Argentina has been faring only slightly better. Periods of showers during the last 30 days have been relatively consistent in the state of Buenos Aires. Despite some cold intrusions that have brought some freezing conditions to developing winter wheat, the increased moisture should have winter wheat in good shape.

However, that has not been the case elsewhere. Recent showers during the last seven to 10 days have been beneficial across the country, but most of Argentina's primary crop areas are in drought. The recent showers have been enough to promote planting and early germination, but subsoil moisture is likely lacking.

Satellite images dated on Oct. 18, the most recent image available, showed all but Buenos Aires at less than 50% of normal soil moisture. Current forecasts call for some showers over the middle of the country on Wednesday, but that is followed by almost a week of dryness.

Should the dryness continue further, the available topsoil moisture will be depleted quickly with stress to developing summer crops likely.

Information regarding Brusberg's research can be found here:…

John Baranick can be reached at


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