The heat wave hitting the state of Rio Grande do Sul -- which usually has milder temperatures than regions further north -- comes after historic floods in the state in 2024 that left more than 180 people dead.

The start of the school year was pushed back a week at the request of a teachers' union, which filed a complaint saying there was "lack of adequate ventilation and sufficient water sources" for students.

"In compliance with the decision of the Court of Justice of the State of Rio Grande do Sul, there will be no classes in the 2,320 schools of the state network this Monday," the education secretariat said in a statement.

The suspension of classes affects around 700,000 students.

The teachers' union hailed the decision as "a fundamental victory for the safety and well-being of the entire school community."

The state government, however, appealed the move and hopes to have students return before February 17.

"The local government is building a resilient school model, adaptable to climate change, with adjustments to school infrastructure," said the education secretariat.

Brazil's national meteorology institute has forecast temperatures of up to 40 degrees Celsius (104 degrees Fahrenheit) and issued a red alert for some parts of the state.

Brazil has been hit by several climate extremes in recent years, from floods to droughts and severe fires, which experts have said are exacerbated by climate change.