A new update to the weather forecast for the summer shows a modification compared to the forecast that was in place until November. And that change could play in favor of a slightly more benevolent climate, especially for the eastern part of the country.
In these first days of the month, as is customary at the beginning of each month, the National Mereorological Service (SMN) published the data for the next quarter, which in this case covers from the beginning of December to the end of February.
The new data indicate a change with respect to the temperatures that the people of Buenos Aires and Buenos Aires would have to endure during the coming summer. The main causes, according to experts, are linked to the temperature of the ocean and the forecast of more abundant rainfall.
The fundamental difference with respect to the last climatological report published in November (and which covered until the end of January) is that now in the aforementioned area an excess of heat is no longer expected, but the trend is at the threshold of normality.
Last month's report indicated that the entire central area of the country was likely to have above-normal temperatures. That has now changed and there is talk of normal values for the time.
Heat wave in January 2023 in Plaza de Mayo, when high temperatures hit hard. Photo: EFE
This modification favors the Capital area, Buenos Aires suburbs and the Atlantic coast. In other areas of the country, the chances of occurrence of abnormal phenomena also changed, but in reverse. In the Patagonian Andes, where until last month normal temperatures were expected for the summer quarter, it is now announced that the marks will be higher.
On the other hand, in the Patagonian area near the Atlantic, the forecast has not changed and continues with a forecast of normal temperatures for the season.
Another area showing changes is Mesopotamia, which has also turned to normal values for the summer. There, the main concern is the flooding due to rains: the El Niño phenomenon is already wreaking havoc and the trend indicates that the next quarter will be rainy.
That is the area of the country where the rains will have the greatest impact, especially in Entre Ríos, while in the central-eastern area (which includes the AMBA and the Coast), rainfall is expected to be above normal but not so much.
Returning to temperature, the most extreme heat marks in the country are expected for the north and northeast of the country. Even in the Cuyo region, the climatic anomaly (with values above normal) is estimated to be greater than in the Argentine coastal area.
These last-minute changes also pose a scenario of transitory uncertainty for some areas of the country and the temporary absence of a marked trend. There, the weather map appears directly blank. It occurs in the central area (part of La Pampa, west of Buenos Aries, east of San Luis and Córdoba), which until last month marked a summer with above-normal temperatures.
The sea and the rains
The modifications now reported by the SMN could be linked to a variable that – also in recent days – was highlighted in a climate report by the Rosario Stock Exchange, which indicates that the temperature of the Atlantic Ocean in Argentina remains very cold, unlike what is happening in Brazil.
That situation is what would be allowing the entry of fresh air (the quasi-autumn day of this Sunday was an example), which acts as a moderator of temperatures.
However, the same report also warns that this phenomenon is beginning to lose intensity for the summer, which could lead to the current situation - which even shows some days of minimum temperatures below normal for this time of year - tending to change.
Marcelo Madelón, a meteorologist with a degree in the Environment, told Clarín more data to explain this change in the climate trend: "Why were there changes in the center and east of the country and the temperature is not going to be higher? You have to relate it to what is expected for the rains, which are going to be more abundant than normal."
Madelón argued: "As next summer is going to be a rainier summer, with more cloud cover, it is very likely that maximum temperatures will decrease. That will influence the average and will mean that instead of being a hotter time than normal, it will end up being normal, according to the months of December, January and February."
The expert added: "The northwest and west of Patagonia are going to be drier, with less cloud cover and therefore the temperature is going to be higher than normal. Here again we see the logical relationship between rainfall and temperatures. That is why, in these last two years of drought we have had heat waves and extreme temperatures, with historical records in the 2022-23 season."
Regarding the temperature of the Atlantic, Madelón said that "the current reports are based on a comparison between the temperature of the sea in Brazil, which is between 26 and 27 degrees in the coastal zone, and that of the Argentine sector, which is now between 18 and 19 degrees in December. That big difference makes the air coming in from the sea in Brazil much warmer than the air coming in from the sea in Argentina."
Bathers in Ipanema, Rio de Janeiro, in the middle of a November heat wave. Photo: EFE
The specialist agreed with the Rosario report that "it is to be expected that as the days go by, due to the simple fact that summer arrives, the temperature of the sea surface on the Argentine coasts will rise a couple of degrees to reach values of between 22 and 23 degrees, depending on the beach."
Despite this expected slight increase in water temperature, Madelón continued, "when there is wind from the east or southeast, it will produce a cooling effect in Argentina, something that does not happen in Brazil, which has had several heat waves."
This difference between the temperature of the sea in Brazil and Argentina, the expert concluded, has nothing to do with the effect of El Niño in both geographies: "The Brazilian Atlantic has a current of warm water that comes from the north and its origin is actually Africa. When this current hits the coasts at the height of Recife, it turns southwards, giving rise to the warm current from Brazil, which does not enter Argentina fully because we have a remnant of cold water that comes from the south through the Malvinas current."