The January 2010 Rio de Janeiro floods and mudslides was an extreme weather event that affected the State of Rio de Janeiro in Brazil in the first days of January 2010.

[2] The worst affected municipality was Angra dos Reis, about 150 kilometres (93 mi) southwest of the city of Rio de Janeiro.

[5] Brazil's only functioning nuclear power plant, Central Nuclear Almirante Álvaro Alberto, is also located within the municipality: plans were made for a temporary shutdown, as blocked roads would make any evacuation difficult or impossible in the event of an incident at the plant.

[2] In Rio Grande do Sul, at least seven people died and 20 went missing after a bridge collapsed due to heavy rains.

[6] Around 60 tons of dead fish washed up in a lagoon in Rio de Janeiro beginning in January,[7][8][9] possibly as a result of local ocean anoxia caused by algal blooms triggered by increased eutrophication from the excess run-off produced by the flooding.