From the article:
The state is at a geographical meeting point between tropical and polar atmospheres, which has created a weather pattern with periods of intense rains and others of drought.
Local scientists believe the pattern has been intensifying due to climate change.
Heavy rains had already hit Rio Grande do Sul last September, as an extra tropical cyclone caused floods that killed more than 50 people.
Two people walking over debris in front of houses.
Rio Grande do Sul's civil defence authority said 68 people were still missing.(Reuters: Diego Vara )
That came after more than two years of a persistent drought due to the La Nina phenomenon, with only scarce showers.
President Luiz Inacio Lula da Silva travelled to the state on Thursday to visit affected locations and discuss rescue efforts with the governor.
Back in Brasilia, Mr Lula vowed on Friday that his government would support local rescue and reconstruction efforts.