The India Meteorological Department has removed a red weather alert from all districts, though some areas are still under water.
India's air force and navy helicopters are airlifting stranded people from rooftops, and dropping food supplies to those they cannot yet reach.
More than 350 people have died in the floods. Thousands remain marooned.
Officials said rescue teams are focused on the riverside town of Chengannur, where as many as 5,000 are feared to be trapped.