Rio had only 7 days without rain in September and October; El Niño can influence the weather

The closed weather occurs amid a period of high volumes of rain in the capital of Rio de Janeiro. In September, Rio recorded the highest accumulation for the month since the beginning of the Alerta Rio historical series, in 1997. There were only four days without rain that month.

In October, the scenario continued to be rainy. According to Alerta Rio, the month was already, until the 27th, the fourth wettest October in the historical series, which began in 1997.

The trend, according to researcher at the Federal University of Rio de Janeiro (UFRJ) Wanderson Luiz Silva, is that, from November onwards, the rains will become more spaced out, but may occur more intensely and concentrated in short periods.

"The volumes should not be so different from the historical average, neither too low nor too high, but they will start to concentrate a little more intensely in shorter periods. This starts to give rise, when we talk about temperature, to possible heat waves when it doesn't rain", he explained.

The change in rainfall patterns requires attention, especially in areas vulnerable to flooding and landslides. According to a study by the National Center for Natural Disaster Monitoring and Alerts (Cemaden), around 800,000 people live in risk areas in the Metropolitan Region of Rio.

El Niño is a climate phenomenon characterized by the abnormal warming of surface waters in the Equatorial Pacific Ocean. This change influences atmospheric circulation and can modify rainfall and temperature patterns in different regions of the planet.

A bulletin released in October by federal agencies indicated a 95% probability of the phenomenon reaching very strong intensity between October and December 2026. The effects, however, vary depending on the region and also depend on the interaction with other climatic factors.

The researcher highlights that rain also plays an important role in water supply and energy generation. Periods of moderate and constant precipitation help to replenish reservoirs and ensure water is available for drier times.

"When the rain comes, it is to be able to fill the reservoirs and ensure that we have, for example, enough water supply, hydroelectric power generation, for when the rain fails. So we always have to be happy when it is raining, even more so in a moderate and constant manner", he stated.