Severe Tropical Storm Domoina in 1984 caused 100-year floods in South Africa and record rainfall in Swaziland.

[nb 1] After crossing the country, Domoina strengthened in the Mozambique Channel to peak 10-minute sustained winds of 95 km/h (60 mph).

In January and February 1984, conditions were favorable for tropical cyclogenesis in the southwest Indian Ocean, including warmer than normal sea surface temperatures and an active monsoon trough.

[1] On January 16, a spiral area of convection persisted off the northeast coast of Madagascar,[2] associated with the Intertropical Convergence Zone.

[1] That day, it organized enough to warrant a satellite-based Dvorak rating of T2.5, prompting the Réunion Meteorological Service to name it Domoina.

Around that time, the storm had begun moving to the southwest,[2] and MFR estimated that it weakened to tropical depression status.

[4] On January 23, the storm emerged into the Mozambique Channel near Belo, and due to a ridge to the north, it resumed its southwest motion.

[2] On January 25, MFR estimated that Domonia attained peak 10 minute sustained winds of 95 km/h (60 mph) near Europa Island; this made it a severe tropical storm.

The next day, Domonia crossed into Swaziland and subsequently into eastern South Africa, weakening into a tropical depression while passing near Durban.

[4] Throughout its path, Domoina left thousands of people homeless,[7] and caused widespread flooding due to drawing moisture from the Indian Ocean and the Mozambique channel.

[11] As Domoina made its final landfall in Mozambique, it dropped heavy rainfall reaching 430 mm (17 in) in the town of Goba over a five-day period.

[13] Officials later advised residents along the Maputo River to evacuate to higher grounds,[14] and thousands had to leave their houses.

[11] The storm flooded the Maputo, Umbeluzi, Incomati river basins, causing widespread power outages.

[13] The storm left the capital Maputo without clean water for several days after a pumping station was damaged,[8][13] and the main harbor in the city was closed.

[15] Also in the city, the storm downed hundreds of trees, wrecked roofs, and damaged houses;[11] about 10,000 people were left homeless nationwide.

[17] Floods affected the railroad connecting Maputo to South Africa, disrupted the construction of a dam, and damaged portions of a bridge near Boane.

[12] Described as the worst flooding in over 20 years,[15] the precipitation increased levels along most rivers in the country, some of which rose 30 m (98 ft) in a few hours.

The floodplain downstream of the Pongolapoort Dam was inundated to where the Pongola met the Ututu River, which filled many pans – dry lakes – in the region.

[21] Due to the widespread flooding and the remoteness of the worst affected areas, there were minimal measurements on the river flow along the Pongola, although above the Pongolapoort dam, levels reached 13,000 m³/s (460,000 ft³/s), which were 18 times higher than the previous record highest.

With the future threat of Cyclone Imboa, dam levels continued to drop until returning to normal by February 16, despite requests to hold the water to prevent further crop damage.

[22] The South African Weather Bureau considered Domoina as the "first tropical cyclone in recent history to have caused flooding and extensive damage.

[11] Relief items were distributed by both air and road in the weeks following the storm,[20] coordinated by the Swaziland Red Cross and assisted by volunteer organizations.

[22] Local governments coordinated relief efforts in the country, including delivering food and providing shelter for those who lost their homes.