October brings cold front, cyclone, and intense heat to Brazil

The beginning of October 2026 is marked by two cold fronts advancing over Brazil, the formation of a cyclone in the South, and the strengthening of the El Niño phenomenon, which raises temperatures and alters precipitation patterns across much of the territory.

Cold front and cyclone in the South

In the early hours of October 1st, a cold front moves from Paraguay towards the South, Southeast, and Central-West, bringing a risk of heavy rain and storms, especially in Santa Catarina, Paraná, and parts of São Paulo. Between October 3rd and 4th, a low-pressure area evolves and originates a cyclone in the interior of the South, intensifying precipitation and causing thunderstorms, mainly in southwestern Rio Grande do Sul and northern Santa Catarina.

El Niño raises heat across the country

This year's El Niño is considered very strong and is expected to intensify throughout the month. According to Climatempo, the phenomenon raises the average temperature above normal in almost all of the Northeast, most of the North Region, north-central Mato Grosso, the Federal District, and parts of Espírito Santo. In the South, temperatures remain slightly below average due to excessive cloudiness and frequent rains.

Precipitation patterns in major regions

In the South, rainfall remains above average, with more intense volumes in Paraná and Santa Catarina. In the Southeast and Central-West, the rain volume also exceeds the average, with Mato Grosso do Sul, São Paulo, and Southern Minas Gerais standing out. In north-central Mato Grosso, the Jequitinhonha Valley, and northern Espírito Santo, precipitation is slightly below average. In the North, rain showers are irregular and tend to be below average, mainly in Pará, Amazonas, and Roraima.

Risk of storms and extreme phenomena

October typically features intense storms, with heavy rain in short periods, lightning, strong winds, and hail, especially in the states of the South, Southeast, and Central-West. The combination of the cold front, the cyclone, and available moisture increases the likelihood of severe events in these areas.

Expectations for Northeast and North

In the Northeast, the month remains dry and very hot, with temperatures that can reach almost 40 °C in inland Piauí, western Bahia, and southern Maranhão. Small rain showers may occur in south-central Maranhão, Piauí, and southwestern Bahia. In the North, rains are sparse and generally remain below average, although showers occur in Acre, Rondônia, Amazonas, Roraima, and northwestern Pará.

With information from Canal Rural, Climatempo, G1.