Extreme Rainfall in Rio Grande do Sul: Multiple Factors at Play

In recent days, Rio Grande do Sul, a southern state in Brazil, has experienced extreme rainfall. Meteorologists from the National Center for Natural Disaster Monitoring and Alerts (Cemaden) and the National Institute for Space Research (Inpe), both research institutions affiliated with the Ministry of Science, Technology, and Innovation (MCTI), have been closely monitoring the situation.

Santa Maria (RS). Photo: Brazilian Air Force.

Rainfall Volumes 

Over a 72-hour period, extreme rainfall volumes in the regions of Santa Maria and Caxias do Sul exceeded 400 mm. These measurements were recorded between 6:00 AM on Monday, April 29, and 6:00 AM on Thursday, May 2, by Cemaden’s monitoring stations.

Simultaneous Atmospheric Phenomena 

Multiple atmospheric phenomena are simultaneously affecting the region. These include:

  • Heatwave: A high-pressure system with warm and dry air has prevented cold fronts from advancing into the area.
  • Slow Evolution: The basin of the Rio Uruguai, due to its larger size, experiences slower changes in water levels, leading to potential flooding.


The meteorological models predict that extreme weather conditions will persist over the coming days. Accumulated rainfall may reach or exceed 250 mm by Saturday, especially in the central-northern portion of Rio Grande do Sul. Additionally, significant precipitation is expected in the western and southern regions of Santa Catarina. Starting from Sunday, the situation is likely to gradually weaken, with intermittent rainfall alternating with dry periods.

Alerts and Precautions

The Cemaden has issued alerts classifying the risk of mass movements as “Very High” in several mesoregions, including the Metropolitan Porto Alegre area and other parts of Rio Grande do Sul.

Continuous updates on alerts are available on the Cemaden website.

Extreme rainfall events in Rio Grande do Sul result from a combination of atmospheric factors. As authorities and communities respond to the challenges posed by these heavy rains, monitoring and preparedness remain crucial.

For more information, you can visit the official MCTI website.