INTA estimate a variable spring -with La Niña- and a summer with neutral weather

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After a wet winter with short-term rainfall events that generated flooding and excesses in different areas of the agricultural region, a campaign with variability in water availability is expected. Specialists from INTA Castelar anticipate the forecasts for the spring and summer to define the agronomic decisions and strategies for the 2025/26 thick campaign.

The El Niño-Southern Oscillation (ENSO) phenomenon has been in its neutral phase since autumn, but the outlook for this month of September reinforces the possible presence of a brief period with La Niña conditions during the spring. After a wet winter with short-term rainfall events that generated flooding and excesses in different areas of the agricultural region, a campaign with variability in water availability is expected.

“While this cooling event can affect the climate during this agronomically key time in the this agricultural region, it is important to remember that we start from a high recharge situation of the profile in the vast majority of the areas unlike other campaigns and springs with oceanic cooling forecast, but scarce or deficit water storage on the ground,” said Pablo Mercuri, director of the Center for Natural Resources Research (CIRT).

The region went through an autumn and winter characterized by an exceptionally high water supply, with rainfall well above normal values in many locations. According to Mercuri: “This situation generated a high availability of water stored in the soils at the regional level, a condition that has not been recorded since the 2015-16 campaign and that represents an extremely positive factor for the planning of the planting of coarse harvest crops.”

Mercuri pointed out that the favorable behavior of the rains allows the productive areas of the center of Argentina not to present limitations for the planting of early and long-cycle corn. He explained that winter cereals are in the cane period and in full tillering in the southern area of the Province of Buenos, and the pastures show vigorous growth with a high supply of green matter, while the soils are well recharged to give continuity to the campaign.

“However, certain areas face complex situations,” said Mercuri, who listed that this especially happened in the center, center-north and center-west of the Province of Buenos Aires – generally within the Salado River basin – the concentration of high-volume rainfall events generated flooding, flooding and saturated soils. However, “during September there have been improvements due to the substantial increase in evapotranspiration that is recorded at this time and a reduction in areas with surface water was observed, the situation requires continuous monitoring,” said the director of CIRN.

“The current water balance presents a regionally favorable outlook that opens up important opportunities for the 2025/26 campaign, although with specific challenges that require agronomic strategies, such as management by environments”, Mercuri said.

Quarterly Outlook
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For the quarter that we are going through September-October-November, in the southern and eastern area of the Pampas Region and the Littoral, a normal rainfall offer for the season is expected with a greater probability, of 40%, according to information from the National Meteorological Service (SMN).

According to Natalia Gattinoni, a specialist at the Institute of Climate and Water, “in statistical terms, for example, in areas of Junín, Province of Buenos Aires, the normal range of rainfall is between 220 and 320 millimeters and towards areas of Coronel Suárez between 170 and 250 millimeters.”

On the other hand, from the agronomic point of view “the distribution of rainfall in the quarter will be key, and here it will be necessary to consult the short-term forecasts since this perspective does not provide any information on that distribution,” Gattinoni stressed.

Regarding temperatures, Gattinoni indicated: “The possibility of the occurrence of thermal values between normal to warmer for this spring and summer is greater, particularly over the center and east of the country.”

The Department of Atmospheric and Ocean Sciences of the University of Buenos Aires added information on extreme events and indicates that the chances of extreme events of maximum and minimum temperatures are lower. Although its occurrence is low, INTA recommended consulting short-term forecasts where updated information is provided on the occurrence of extreme thermal events.

From the Center for Research on the Sea and the Atmosphere (CIMA/CONICET-UBA) they estimate to go through a period with normal to deficient rainfall in a large part of the agricultural area, especially over the north of the Litoral, a water panorama that is influenced by the possible development of a cold phase of the ENSO during that period, although with some dispersion among the models in terms of its intensity.

Likewise, this signal would be reinforced with the influence of the Indian Ocean Dipole (DOI), another ocean-atmosphere phenomenon that is expected to transit conditions that are usually associated with less rainfall during the spring over the east of the country’s main agricultural region.

Productions towards the northwest of Argentina could be favored with the possibility of a spring with normal to higher rainfall. INTA also highlight in this type of climatic context that the forecast rainfall patterns present greater spatial variability.

“We believe that it will be key to monitor the climate update during these months, being able to adjust or modify certain agronomic strategies according to the soil and climatic context of the region,” Gattinoni stressed.

With the information available to date, INTA experts indicated that, “for the summer and early autumn, the return to neutrality of the ENSO phenomenon and the DOI is favored and therefore this is reflected in chances of normal rainfall and even with a certain probability to higher, for the season in the center and east of the country.”

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