Fourth heat wave in Brazil: why is the phenomenon so frequent? | Weather forecast

The weather forecast indicates the formation of a new heat wave in Brazil. According to meteorologists, it is the fourth this year. temperatures should increase, mainly, in the region between São Paulo, Paraná, Mato Grosso do Sul, Minas Gerais and Goiás, where thermometers should register temperatures above 35 °C.

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What explains the fourth heat wave in this first half of the year? One of the factors is the climate phenomenon El Niño. “We are with him in action. It has little strength, but it still works. And it is because of this that the heat wave will be less intense than what we saw in spring, when the phenomenon was much stronger”, he explains. Marco Antônio dos Santosagrometeorologist at Rural Clima.

Another factor contributes to more frequent and intense heat waves in the country, according to Nadiara Pereira, meteorologist at Climatempo: global warming. She highlights that the condition was already expected for the last spring-summer El Niño season in the Southern Hemisphere.

“Year after year, we have been observing a warmer global atmospheric condition, and El Niño, as it is a warming event resulting from a positive temperature anomaly in the Equatorial Pacific Ocean, which is the largest ocean mass, transmits this heat well to the atmosphere. So, it becomes more heated, increasing heat waves”, he says.

Temperatures are expected to remain high until at least the first week of May, adds Willians Bini, CCO at climate monitoring platform FieldPRO. He points out, however, that this heat wave has important differences from previous ones. One of them is to occur in a period of lower humidity. “From now on, we’re starting to talk about low humidity. We’re already starting to talk about an additional ingredient, different from what we had,” he explains.

Another difference is that temperature peaks should not be as high, compared to the other three heat waves already recorded this year.

“Heat spikes are not that common, but quite significant if we look at a historical condition. It will hit the Southeast and part of the Midwest well. A heat wave, we always compare it with what would be normal during that period of the year. At this time of year, average temperatures are already lower. So, 32ºC, 33ºC, it’s already a heat wave”, he says.

In agricultural production regions, rising temperatures should not harm crops or field activities, assesses the meterologist. He points out that this drier period was preceded by above-average rainfall throughout the month. “This drier weather does not mean such a bad climate condition for agriculture,” he says.

What to expect in the coming months?

Marco Antônio dos Santos, from Rural Clima, states that climate models do not indicate, at least so far, the formation of other waves for the period between autumn and winter. However, he points out, the same references did not show, around 30 days ago, the occurrence at the turn of April to May.

“As long as El Niño does not completely weaken and La Niña begins to influence the climate, we cannot completely eliminate the chance of new waves”, he points out.

The La Niña phenomenon is characterized by a drop in the temperature of the equatorial portion of the Pacific Ocean to 0.5ºC. When it is active, the volume of rain tends to decrease in the South of Brazil and increase in the North and Northeast. In the Southeast and Central-West regions, there are chances of colder and rainier periods.

Nadiara Pereira, from Climatempo, in turn, does not rule out the occurrence of heat peaks in the month of May, the so-called summer season, as has been recorded in previous years.

“With La Niña, the chances of heat waves like those that are happening will reduce, but the presence of heat next month cannot be ruled out, even if El Niño is not in force. However, I anticipate that the chance of a new strong and lasting wave begins to decrease considerably in the transition from autumn to winter. And in addition to us entering a cold period, there is also a changing condition in the Pacific Ocean”, he concludes.