Inmet: Weather forecast for the first week of 2026

The National Institute of Meteorology (Inmet) predicts a scenario of contrasting climates in Brazil between December 30, 2025, and January 5, 2026, highlighting heavy rainfall in the South and Midwest and the formation of a heat wave in areas of the Southeast and Midwest during the New Year's period.

No Sul Across the country, the recurring approach of frontal systems and the action of low-level jet streams should cause intense rainfall until January 3rd, mainly in northern Rio Grande do Sul, Santa Catarina, and eastern Paraná, where accumulations could exceed 150 millimeters in seven days. Two episodes of more significant rainfall are expected: one at the beginning of the week and another on January 2nd. In south-central Rio Grande do Sul, the weather tends to remain more stable, with minimum relative humidity around 35% during the afternoons.

Na Midwest regionThe highlight is for western Mato Grosso and Goiás, especially in northern Goiás, where accumulated rainfall could exceed 200 millimeters, intensifying from January 3rd. Conversely, Mato Grosso do Sul is expected to experience a drier period, with accumulations below 50 mm and minimum relative humidity below 30% in areas of the western part of the state.

No SoutheastThe first half of the week will be marked by drier weather, high temperatures, and low air humidity, due to the presence of an anomalous high-pressure system in the middle and upper levels of the atmosphere, which hinders the advance of cold fronts. This pattern favors the occurrence of a heat wave, with highs that could reach 39°C in Minas Gerais and Rio de Janeiro, values ​​more than 5°C above the climatological average. From the second half of the week onwards, the formation of a moisture channel should favor the return of rainfall, a reduction in temperatures, and an increase in humidity in the region.

No North In the country, rainfall is concentrated mainly in Amapá, Amazonas, Rondônia, southern Pará, and Tocantins, influenced by the availability of heat and humidity and the approach of the Intertropical Convergence Zone (ITCZ). In these areas, accumulations can vary between 80 and 100 mm in seven days. Despite this, northern Pará and Roraima should face drier periods, with minimum relative humidity around 35%.

Na North East RegionThe start of the week will be influenced by the action of an upper-level cyclonic vortex (VCAN), with forecasts of showers in Maranhão, southwestern Piauí, western Bahia, and the interior of Pernambuco, some accompanied by thunderstorms. In the rest of the Sertão region, the trend is for low humidity, with levels below 30%. Temperatures remain high, with maximums close to 40°C in the Sertão, especially in Pernambuco and Alagoas.

In addition to the rain, Inmet (National Institute of Meteorology) is drawing attention to the predominance of high temperatures across much of the country during the second week of summer. The heat wave event is expected to affect areas of Goiás, Mato Grosso do Sul, São Paulo, Minas Gerais, Espírito Santo, and Rio de Janeiro, while the lowest temperatures are forecast for mountainous regions of Rio Grande do Sul and Santa Catarina, where thermometers may register less than 12°C at dawn over the weekend.