Cyclone Off Argentina Drives Front Into Southern Brazil, Triggers Storm Alerts

Overview

• Rio Grande do Sul is under Inmet storm warnings that Thursday classify many zones at danger, with 10 to 60 mm of rain, local peaks near 90 mm, gusts above 90 km/h, and a chance of hail.
• The system is being organized by a deepening extratropical cyclone off Argentina and Uruguay, which stays offshore but strengthens the cold front and drives very strong winds over the Atlantic that may reach about 180 km/h in open sea.
• Forecasts show the front spreading through the South into Santa Catarina and Paraná on Friday and reaching Mato Grosso do Sul and São Paulo on Saturday, with gusts near 80 km/h possible between São Paulo and Rio de Janeiro on Sunday.
• A strong polar air mass follows the front and brings a sharp drop in temperatures with widespread frost risk in the South and the first Amazonian cold surge of 2026 pushing into Rondônia and Acre early next week.
• Separate instability linked to the Intertropical Convergence Zone keeps heavy rain over large parts of the North and Northeast, with Inmet alerts through Wednesday and local warnings in Salvador through Thursday urging people to watch for flooding and use Civil Defense 199 or Fire Department 193 in emergencies.