KANSAS CITY, MISSOURI, US – La Niña still has not evolved after various computer forecast models were predicting it was imminent since last spring. Changes in ocean surface temperatures finally have become significant enough that traditional La Niña-biased conditions are beginning to show up around the world.

An official La Niña event may not ever evolve, or if it does evolve it only will last a month or two because of predicted warming temperatures in the eastern equatorial Pacific Ocean later this winter and spring. 

In the meantime, the significant change in ocean surface temperatures during December has brought rainy weather to Indonesia, South Africa and center-west through center-south Brazil while dryness is evolving in Argentina, Uruguay, southern Paraguay and far southern Brazil.

The drier- and warmer-biased weather expected in portions of South America was expected to become quite significant during the early to middle part of January and possibly into the latter part of the month. Not all the summer crops were planted at the end of December. Early seeded corn and sunflower seed were developing well due to favorable soil moisture and timely rainfall through December. 

Drier-than-usual conditions in late December firmed the topsoil, but good subsoil moisture maintained good summer crop development for well-established crops. In contrast, the more recently planted crops are facing the potential for poor emergence and establishment due to dwindling topsoil moisture. Some delay to late season crop planting is likely because of poor surface moisture that is needed to induce germination and plant emergence. 

Topsoil moisture on Dec. 31 was rated marginally adequate to short, with a few fields very short of moisture. These conditions were occurring with “normal” temperatures. A warming trend in early January along with little to no rain was expected to accelerate the drying trend and topsoil moisture was expected to be rated short to very short in most of the nation except the far west and extreme north by Jan. 9. The following week was expected to see subsoil moisture decline as well, bringing on the first week of general crop moisture and heat stress. 

A single week of stressful conditions will not permanently harm crops, especially if rain develops after that event and temperatures trend cooler. Most of the medium- and long-range forecast models suggested scattered showers and thunderstorms with some slight cooling would occur during mid-January. But with La Niña-like conditions still prevailing, the odds are quite high that declining soil and crop conditions will resume later in the month. 

These conditions not only will impact central and east-central Argentina, but southern Paraguay, portions of Rio Grande do Sul and Uruguay as well. Some drying is possible in Santa Catarina, Parana and Mato Grosso do Sul, though these areas have a relatively good chance for timely rain that will help reduce the potential for serious crop stress. 

There were some signs of possible change noted in early January. The Southern Oscillation Index was falling along with the Antarctic Oscillation index. Both indices suggested weakness in the La Niña-like conditions would show up during mid-January. That implies an opportunity for scattered showers and thunderstorms along with “some” cooling. 

World Weather, Inc. does not expect the weather change to last long, and the relief that occurs will provide only temporary relief. More influence from La Niña-like conditions are expected later this month, maintaining some pressure on production and overall crop health. 

Typically, when La Niña is present, eastern Argentina, Uruguay, southern Brazil and southern Paraguay experience lower yielding summer crops. In some years (usually in a full-blown La Niña event of significance), production can be significantly cut. This year may be different because of highly favorable early-season crop development and the fact that La Niña-like conditions will diminish in February. 

Unfortunately for South American farmers, the break will come after early-season summer crops have reproduced and filled. Late-season crops will have the opportunity for getting timely rainfall and less oppressive heat resulting in better yields. The bottom line is that South America may experience a decline in production potential, but the impact may be relatively light unless conditions stay adverse in February. 

The bigger issue for South America may be on the Safrinha (second season) corn crop that is usually planted in January and February following the soybean harvest. Some of the Safrinha corn will be planted a little late because of delayed seasonal rains and delayed early season soybean planting. In addition to that delay, there is some potential for more delays in early-season soybean harvesting because of too much rain from center-west to center-south Brazil during the heart of January, which is another byproduct of La Niña-like conditions. 

Delays to Safrinha corn planting may lead to a smaller crop if seasonal rains end early or even on time in April. A full-blown La Niña event often will extend the rainy season so that late planting of Safrinha crops has a lower impact than feared. This year’s La Niña-like conditions may not have the same influence, and Safrinha crops could be impacted by limited soil moisture cutting into production somewhat. 

The bottom line is that conditions in South America have been ideal since late October, but trouble is brewing for the month of January that may pressure eastern Argentina, Uruguay, Rio Grande do Sul and Paraguay summer crop yields lower while “possibly” impacting the Safrinha crop with lower yields. The impact of all this may not be as devastating as it sounds, but most likely a short-term weather rally will move commodity futures prices higher until better rains return.  

The bottom line is that South America may experience a decline in production potential, but the impact may be relatively light unless conditions stay adverse in February. 

Drew Lerner is senior agricultural meteorologist with World Weather, Inc. He may be reached at worldweather@bizkc.rr.com. World Weather, Inc. forecasts and comments pertaining to present, past and future weather conditions included in this report constitute the corporation’s judgment as of the date of this report and are subject to change without notice.