An extratropical cyclone and an associated cold front are bringing intense storms, hail, and strong winds to southern Brazil [1, 2].
These weather patterns are significant because they produce out-of-season rainfall and high wind speeds that can disrupt infrastructure and safety across multiple regions.
The weather system began impacting the region on Monday, May 25, 2026 [3]. The resulting instability is driving a cold front that is expected to affect four states: Rio Grande do Sul, Santa Catarina, Paraná, and Mato Grosso do Sul [2].
Meteorological data indicates that wind speeds could reach up to 100 km/h [4]. Some areas are expected to see rainfall accumulations of up to 100 mm [4]. These conditions are characterized by intense storms and a heightened risk of hail [1, 2].
While early reports focused on the southernmost regions, the system has expanded its reach. The cold front is now advancing specifically into Paraná and Mato Grosso do Sul [2]. In the South, severe weather is expected to persist for two days, specifically on Wednesday and Thursday [5].
The instability is the direct result of the extratropical cyclone pushing the cold front forward. This movement creates a clash of air masses that triggers the severe storms and unseasonable rain [2, 4].
“Wind speeds could reach up to 100 km/h”
The convergence of an extratropical cyclone and a cold front during this period indicates a volatile atmospheric state in southern Brazil. The presence of out-of-season rain and high wind speeds suggests a disruption in typical climatic patterns, increasing the vulnerability of agricultural zones and urban centers in the four affected states to flash flooding and wind damage.
