New cyclone off southern Brazil brings storms as cold front moves toward Southeast

A new extratropical cyclone formed off Brazil's southern coast on Monday, August 31, generated by the contrast between warm and cold air masses, according to meteorological outlet G1, citing data from Climatempo. The cyclone is giving rise to a cold front that will bring a major weather shift to much of the country in the first days of September.

Storms and flood risk in the south

The greatest risk of severe weather on Monday afternoon was concentrated in Santa Catarina, northern Rio Grande do Sul and Paraná, where heavy rain, hail and strong wind gusts were possible. G1 reported that rainfall in parts of Santa Catarina could exceed 100 mm, and the formation of tornadoes could not be ruled out in some areas of Santa Catarina and Paraná. Brazil's National Institute of Meteorology (Inmet) confirmed that on Tuesday, September 1, morning showers with isolated thunderstorms would hit Paraná, Santa Catarina and eastern Rio Grande do Sul, with the instability gradually shifting toward the Southeast region in the afternoon.

Rain spreads to the Southeast

On Tuesday the cold front will also bring rain to São Paulo and southern Rio de Janeiro, while on Wednesday, September 2, rain will hit Rio de Janeiro, southern Minas Gerais and southern Espírito Santo more intensely. According to Inmet, the maximum temperature in the city of São Paulo on Tuesday will not exceed 22°C, and the minimum on Wednesday is expected around 12°C.

Heat persists in central and northern regions

Before the cold sets in, strong heat will persist in parts of the country. G1 reports that areas of Mato Grosso, Goiás, Tocantins and Piauí could approach 40°C on Monday, and Cuiabá, the capital of Mato Grosso, recorded 41.2°C on Sunday — a new 2026 record for the city. Separately, Inmet states that on Wednesday, September 2, the northeastern city of Teresina, in Piauí, could reach up to 41°C, while northern cities such as Rio Branco, in Acre, will see nighttime lows around 22°C.

Temperatures drop in the south and parts of the Southeast

After the rain passes through the south, temperatures will drop noticeably — in the mountainous areas of Santa Catarina, lows could approach 5°C on Wednesday. In Minas Gerais, lows around 10°C are expected on Wednesday, and even lower, around 6°C in some mountain areas, on Thursday, September 3, according to G1. At the same time, northern Minas Gerais could still see highs of up to 38°C during the week, showing that the cooling effect will not be uniform across the region.