Africa: Annual rainy season to occur across parts of eastern regions through December

Event

Eastern Africa's annual rainy season will run through December, bringing an elevated threat of flooding and landslides/mudslides in some locations. The affected area includes Burundi, Kenya, Madagascar, Malawi, Mayotte, Mozambique, Rwanda, South Sudan, Tanzania, and Uganda. Heavy downpours, flooding, and landslides could affect many areas' business, transport, and utility services. Localized disruptions could persist well after hazardous events have concluded; floodwaters may take days to subside, and clearance of resulting mudslide debris may take weeks. Rural communities and informal settlements often suffer the most significant damage and casualties during such events due to poor infrastructure.

Forecast models indicate below-average rainfall across Burundi, southern Kenya, northern Madagascar, northern Mozambique, and Tanzania, while normal to above-average rainfall is likely across northwestern Kenya, southern Madagascar, southern Mozambique, central and southern South Sudan, and Uganda.

This risk of flooding is highest in low-lying communities near watercourses in recognized floodplains. Eastern Africa has several major rivers and lakes, including the Limpopo, White Nile, and Zambezi rivers, as well as Lake Victoria and Lake Malawi, which could flood during periods of intense rainfall. Flash floods, which can occur with little to no warning, often threaten 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 regions.

Transport
Floodwaters and debris flows may render some bridges, rail networks, or roadways impassable, impacting overland travel in and around affected areas, especially 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 some low-lying routes that become inundated by floodwaters.

Severe weather could also 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 might 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 have mixed with floodwaters can become trapped in open areas when inundations recede. These stagnant pools often become a breeding ground 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.