Will the heat wave let up? Check the forecast.

247 - After a week marked by record temperatures in Southeast capitals, such as São Paulo, Rio de Janeiro and Belo Horizonte, storms are back in the region starting this Friday (24). The information is from Climatempo, which also predicts changes in the weather for the South region, with heavy rains, strong winds and a drop in temperatures in the coming days.

In São Paulo, thermometers reached 33,9°C last Wednesday (22), while Rio de Janeiro came close to 39°C. Belo Horizonte also recorded successive heat records, with highs above 35°C. However, the arrival of rain will bring partial relief. “Temperatures should drop by around 4 or 5 degrees by the weekend, so it will get a little less hot as the days go by,” says meteorologist Fábio Luengo, from Climatempo.

Storms and risks

According to the forecast, the three southern states – Paraná, Santa Catarina, and Rio Grande do Sul – are expected to face heavy rainfall, accompanied by hail and winds that could reach 80 km/h. “This Friday, the storms will return in full force to the three southern states. The same situation is expected for São Paulo, generally with somewhat more isolated rainfall, reaching as far as Mato Grosso do Sul,” Luengo explains.

Storms can cause flooding, fallen trees, and other disruptions, especially in the South. In the North and Northeast, although heavy rain is also expected, the downpours are likely to be more localized and cause less damage. In these regions, the phenomenon responsible for the intense rainfall is the Intertropical Convergence Zone (ITCZ).

The impact of adiabatic heating

The intense heat recorded earlier this week in the Southeast region is related to a phenomenon known as adiabatic heating, according to Climatempo. This process occurs when air descends from mountains, compressing to maintain pressure, which causes an increase in temperature.

“On the coast of São Paulo, for example, when the northwest wind blows, the air descending from the Serra do Mar mountain range heats up by about 1°C for every 100 meters. Between São Paulo and the Baixada Santista region, which has almost 800 meters of altitude difference, the temperature on the coast can easily exceed 38°C, while in the capital it is around 30°C,” explains meteorologist Fábio Luengo.

This phenomenon, combined with decreased cloud cover, the absence of cold winds of polar origin and cold fronts, was a determining factor in the high temperatures in the Southeast this week.

Weekend forecast

For Saturday (25), a new cold front forms, maintaining the risk of storms in the South, in São Paulo and in Mato Grosso do Sul. On Sunday (26), the storms should advance to Minas Gerais, Espírito Santo and part of the Central-West, including Goiás and the Federal District.

Meanwhile, in the North and Northeast, rain is expected to continue affecting states such as Amapá, Pará, Maranhão, Acre, Amazonas, and Rondônia. Despite the intensity, "the trend is that they will be isolated and not cause much damage," predicts Luengo.

The relief brought by the rains brings hope after days of extreme temperatures, but also demands attention to weather conditions in the most vulnerable areas. The year 2024, already considered the hottest in history according to a European observatory, continues to pose challenges to living with extreme weather events.