Potential Excessive Rain in Brazil and Dryness in Argentina

The majority of Brazil has seen below-average precipitation as it nears the end of its first-crop corn and soybean planting season. 

According to a report by the Foreign Agricultural Service (FAS) from the U.S. Department of Agriculture (USDA), Brazil soybean production for the 2024/2025 marketing year is forecast at 169 million metric tons, up 16 million metric tons from last year. 

David Tolleris, meteorologist and owner of wxrisk.com, said that a wet pattern is predicted for parts of Brazil in the next two weeks. He said the second week shows northern São Paulo receiving up to 12 inches of rain, according to the Global Forecast System.

“That’s too much rain in one week,” Tolleris said. “We also see 8-inch rains in Mato Grosso and Goiás.” 

Tolleris said Brazil has been drier than normal the past few weeks, and attributes the predicted shift in precipitation to a weather cycle called the Madden-Julian Oscillation (MJO). 

“The MJO has been in phases that have favored above-normal rainfall in southeast Brazil and northeast Argentina, and below-average rainfall in the main grain areas in Brazil,” Tolleris said. 

With rain in the forecast, Tolleris said farmers who aren’t done planting are in a “race against the clock” and may face delays. He also thinks that the shift to a wetter weather pattern may affect the predicted record soybean production. 

“They have to get their planting done now, because if the model is right, late planting in the first half of January is going to be a problem,” Tolleris said. “They’ve got to get everything done in the next seven days.” 

While Brazil faces excessive rainfall, Argentina has the potential to be dry. Tolleris said the MJO model “dramatically shuts down” the potential for rain in January for Argentina and southeast Brazil. He said the weak La Niña also contributes to drier conditions in Argentina. 

“There’s a problem for Rio Grande do Sul and Argentina because they’re in a dry cycle, and the weak La Niña hurts them as well,” Tolleris said. 

Tolleris said the possibility of excessive rainfall in Brazil and continued dryness in Argentina may be the difference between a predicted record crop and a “good” crop. 

“Everyone’s talking about a record crop coming out of Argentina and Brazil, but these forecast models and the MJO are showing that the ‘record crop’ may be in trouble,” Tolleris said.