Unseasonable warmth rose across northern Argentina, Uruguay, southeastern Brazil and Paraguay over the past several days but change is on the way.
This heat will come to an end as a potent cold front rushes northward across the region, triggering gusty thunderstorms and flooding downpours.
Severe thunderstorms and heavy rain will develop across Buenos Aires state Tuesday afternoon, spreading northward Tuesday night into Wednesday. The worst conditions will impact Buenos Aires, Argentina, and Montevideo, Uruguay, during this time before moving farther north across Uruguay and into the state of Rio Grande do Sul, Brazil, Wednesday night.
Other major cities that can expect severe weather in the coming days include Cordoba and Rosario in Argentina and Porto Alegre in Brazil.
The biggest concern will be torrential rainfall which could result in flash flooding across the region. However, the strongest storms can contain damaging wind gusts to 80 kph (50 mph) and hail.
The threat for flooding later this week will be centered from southeast Brazil into Paraguay and Bolivia.