Ag Weather Forum

A More-Favorable South America Forecast

Mike Palmerino
By  Mike Palmerino , DTN Senior Ag Meteorologist
Early-December rain in the primary Argentina crop areas was light, with only isolated amounts of one inch or more. (NOAA graphic by Nick Scalise)

After several weeks of a drier than normal pattern in central Argentina, along with a turn to hotter temperatures during the past week, rain is needed to prevent losses to early-planted corn which is approaching reproduction. Forecast models all week have been indicating the chance of some moderate to heavy rain in the major Argentina corn and soybean areas on Saturday. Timing will be crucial with this system, as it will be a fast mover, with some areas likely missing out on significant rainfall.

Rain events bear close watching, as there is still a long way to go with the growing season in Argentina. Corn and soybean planting are running at around 55% complete as of December 7. This is close to last year's pace. Dryness would need to hold well into January to produce major crop losses to corn, and into February for soybeans. However, La Nina conditions are occurring in the equatorial Pacific Ocean, and studies have shown that La Nina is associated with drought in central Argentina, so this cannot be ruled out.

Meanwhile, in central Brazil, the rainy season remains well-established. Frequent rain episodes in central Brazil favor developing soybeans in the major growing areas, including Mato Grosso. After a hot and dry start to the growing season, conditions have turned quite favorable. We were concerned that a late planting of the soybean crop might impact double-cropped corn acreage. This seems less likely now, as rapid planting took place upon the arrival of the rains; also, a La Nina Pacific temperature event may extend deeper into the Southern Hemisphere fall season, which would be very favorable to double-crop corn.

Southern Brazil has recently turned hotter and drier than normal in Rio Grande do Sul. The drier trend is leading to soil moisture loss. This situation bears watching, as La Nina can also produce drought conditions in Rio Grande so Sul. However, with nearly 20% of the crop remaining to be planted, and the early stage of development of the planted crop, drought conditions would have to continue well into January to have any significant crop impact.

Mike Palmerino can be reached at



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