South America: Annual rainy season underway in the region through March 2021

Event

The annual rainy seasons in Brazil, Peru, Paraguay, Bolivia, and Uruguay will run through March 2021, bringing an elevated potential for flooding, landslides, and mudslides regionwide, especially in the Amazon region. Forecast models indicate that average to above-average rainfall is likely across central South America, including Bolivia, Brazil, and Paraguay, during the rainy season, while below-average rainfall is forecast for Peru.

Heavy downpours, flooding, and landslides could affect business, transport, and utility services in many areas. Localized disruptions could persist well after hazardous environmental events have concluded; floodwaters may take days to subside and resultant mudslide debris may take weeks to be cleared. Rural communities and informal settlements often suffer the greatest damage and casualties during such events due to poor infrastructure.

The risk of flooding is highest in low-lying communities near watercourses in recognized floodplains. South America has several major rivers, including the Amazon, Madeira, Parana, Tocantins, Rio de la Plata, and the Sao Francisco rivers, that could flood during periods of intense rainfall. Flash floods, which can occur with little-to-no warning, often pose a threat to communities downstream of major rivers or dams in the event of infrastructure failure. Urban flooding is possible in areas with poorly maintained or inadequate drainage systems, while storm surges may trigger flooding in coastal areas. Landslides and mudslides are possible in hilly and mountainous areas.

Transport
Floodwaters and debris flows may render some bridges, rail networks, or roadways impassable, limiting overland travel in and around affected areas. These effects will be especially pronounced in rural areas, where infrastructure is already of a poor standard. Ponding on road surfaces could cause hazardous driving conditions on regional highways. Authorities could temporarily close low-lying routes that become inundated by floodwaters.

Severe weather could trigger flight delays and cancellations at domestic and international airports. Authorities may temporarily suspend port operations or close beaches if strong winds trigger hazardous sea conditions. Flooding could block regional rail lines; freight and passenger train delays and cancellations are likely in areas that see heavy rainfall and potential track inundation.

Localized business disruptions may occur; some businesses may not operate at full capacity because of flood damage to facilities, possible evacuations, and some employees' inability to reach work sites.

Health
The threat of disease outbreaks is elevated during the rainy season. Backflow from drains that has mixed with floodwaters can become trapped in open areas when inundations recede. These stagnant pools often become breeding grounds for mosquitoes and bacteria, increasing the incidence of insect- and waterborne diseases. Exposure to contaminated water from inundated industrial sites, sewer systems, and septic tanks also poses a significant health threat.

Advice

Monitor local media for updates and advisories on weather conditions. Confirm all transport reservations (air, ground, and maritime) prior to travel. Make allowances for possible supply chain disruptions throughout the rainy season, particularly in areas affected by flooding and or/landslide events.

Avoid low-lying areas near streams, rivers, and other bodies of water, such as reservoirs and coastlines, due to the threat of flooding. Do not drive on flooded roads. Exercise caution in elevated terrain due to the threat of landslides and mudslides. Charge battery-powered devices when electricity is available; restrict the use of cellphones to emergencies only during periods of severe weather. Take precautions against insect- and waterborne diseases. Keep any necessary medications in a waterproof container.

Resources

National Institute of Meteorology (Brazil)
National Meteorological and Hydrological Service (Bolivia)
National Meteorological and Hydrological Service (Peru)
Directorate of Meteorology and Hydrology (Paraguay)
National Directorate of Meteorology (Uruguay)