Polar Cold Freezes Brazil’s South as Atlantic Front and ZCIT Drive Heavy Coastal Rains

Overview

• A polar airmass is over the South and has produced consecutive subzero mornings and widespread geada, with official station lows reported in Vacaria and other Serra towns and authorities continuing cold alerts through the weekend.
• An Atlantic frontal system and the Intertropical Convergence Zone are fueling heavy convective rain and a risk of temporais along parts of the North and the Southeast coast, with some forecasts projecting 50–100 mm accumulations in areas of the Sul and eastern São Paulo.
• States and municipalities have activated emergency monitoring: Rio de Janeiro set a special response scheme and used Cell Broadcast and sirens after the Quitandinha river rose in Petrópolis, while Espírito Santo placed more than 40 municipalities under warning for intense rain and hail.
• The Marinha issued a ressaca warning for the Rio de Janeiro coast with waves forecast near 2.5–3 meters, and local agencies advised swimmers, fishers and orla users to avoid the water and follow safety orders.
• Forecast models and meteorologists project the cold will hold through the weekend and begin weakening from Sunday with continued risk of nighttime frosts, ongoing coastal downpours, and secondary impacts on vulnerable people, crops, power lines and slope stability.