Rain: Southern and Southeastern regions are expected to receive the highest rainfall amounts.

Rain is expected to be concentrated mainly in the South, Southeast, and North regions of Brazil between September 21 and 28, 2026, according to data released by the National Institute of Meteorology (INMET). In the South, Rio Grande do Sul and Santa Catarina may register accumulations exceeding 100 mm, while São Paulo and Rio de Janeiro should also experience high volumes.

According to INMET's numerical model, the highest rainfall totals predicted for the Southern Region should occur mainly in the central and western areas of Rio Grande do Sul and Santa Catarina, with volumes that could exceed 100 mm.

The week begins with strong instability in the Southern Region, especially in the Serra Gaúcha, where rainfall totals have already exceeded 100 mm. Throughout this Monday, the areas with the most significant rainfall will move northward into Rio Grande do Sul, Santa Catarina, and Paraná.

After this period of instability, the weather should remain stable over the Southern Region, without significant rainfall accumulation. Rain will intensify again over the weekend, mainly in the eastern part of the region.

In the Southeast region, the week begins with unstable weather in most states. According to data released by INMET, the highest rainfall totals are expected in São Paulo and Rio de Janeiro, where volumes may exceed 80 mm in some areas.

In other areas of the Southeast, isolated showers are possible, but weekly totals are expected to be less significant. In northern Minas Gerais, the weather will remain stable throughout the period.

In the Northern Region, the highest rainfall amounts are expected in the far northwest and central regions of Amazonas. According to data released by INMET, accumulations could exceed 80 mm in some areas.

In other locations in the Northern Region, isolated showers may occur, but without significant volumes. Accumulated rainfall should be between 5 mm and 20 mm throughout the week.

In the Northeast, rainfall is expected to be more concentrated along the coastal strip. The highest accumulations are forecast for the coast of Bahia, with volumes of up to 20 mm.

In the eastern part of the Northeast region, between Sergipe and Pernambuco, there is a possibility of isolated showers, with accumulations not expected to exceed 10 mm throughout the week. In the interior of the region, the weather remains stable, with no significant rainfall forecast.

In the Central-West region, the most significant rainfall is expected in southern Mato Grosso do Sul. According to data released by INMET, accumulations could exceed 50 mm in some areas.

Throughout the week, there are also indications of isolated showers across much of the Central-West region, including the Federal District. In northern Goiás and northeastern Mato Grosso, however, the weather should remain predominantly stable.

In general, the INMET numerical model forecast indicates that the highest rainfall volumes between September 21 and 28 will be concentrated in the South, Southeast, and North of the country.