A cold front is bringing heavy rainfall and storm activity to southern Brazil with precipitation expected to reach São Paulo by Thursday [1, 4].
The weather system is intensified by El Niño conditions, creating significant instability that threatens infrastructure and public safety in high-risk regions [3].
In Rio Grande do Sul, the instability led to tornado formation in the northwest region on Tuesday, July 28 [1]. This region has faced extreme precipitation recently, with some reports indicating rainfall up to 200 mm [2], while other estimates suggest totals as high as 400 mm between July 16 and July 25 [3].
The front is currently moving north and east. Meteorologists said the system is expected to reach the Southeast, including São Paulo, between the night of Wednesday, July 29, and the early hours of Thursday, July 30 [1, 4].
This pattern follows a series of volatile weather shifts in the region. Earlier in the month, rain began affecting southern São Paulo on July 22 and spread through July 23 [5]. These recurring fronts have maintained a risk of frosts in the south and periodic returns of rain to Rio de Janeiro and Minas Gerais [6].
Local authorities said they continue to monitor the movement of the front as it transitions from the southern plains toward the urban centers of the Southeast [1].
“A cold front is bringing heavy rainfall and storm activity to southern Brazil”
The convergence of a strong cold front and El Niño conditions is amplifying precipitation levels beyond seasonal norms in southern Brazil. The movement of this system toward São Paulo suggests a period of heightened meteorological risk for Brazil's most populous urban areas, potentially leading to urban flooding and transport disruptions.
