Climate change and La Niña fueled deadly southern Africa floods, scientists say

The floodwater reached the roof before dawn.

In the Mozambican coastal city of Xai-Xai, families scrambled up ladders and onto corrugated metal rooftops as a brown torrent roared through the streets below. Fishing boats and makeshift rafts ferried neighbors to safety. In the shallows, rescuers shouted warnings about crocodiles sweeping in from the swollen Limpopo River.

“We thought it would be like other years,” said a resident sheltering at a school turned evacuation center. “But the water kept rising. It didn’t stop.”

Between late December and mid-January, southern Africa was hit by unusually intense and persistent rains that swamped parts of Mozambique, South Africa, Zimbabwe and Eswatini. The heaviest 10-day burst, from Jan. 10 to 19, turned rivers into wide, fast-moving lakes, washed away roads and bridges, and cut off clinics and entire towns.

Health officials say about 1.3 million people have been affected across the region since mid-December. More than 200 people have died, and hundreds of thousands have been forced from their homes. A rapid scientific analysis released at the end of January concludes that human-driven climate change, combined with a natural La Niña climate pattern, made that 10-day deluge significantly more intense than it would have been in the past.

The result is one of the deadliest multi-country flood disasters southern Africa has seen in recent years—and one that scientists say offers a clear example of how a warming planet is reshaping local weather extremes.

A rare storm in a changed climate

The new study by the World Weather Attribution group, a consortium of climate scientists from universities and meteorological agencies, focused on the maximum 10-day rainfall totals recorded over parts of Mozambique, Eswatini, northeastern South Africa and Zimbabwe during the 2025–26 rainy season.

Using historical observations and climate models, the researchers estimated that such an intense 10-day rainfall event now has roughly a once-in-50-years chance of happening in the region’s current climate. They found that global warming of about 1.3 degrees Celsius above preindustrial levels has made these kinds of downpours about 40% wetter on average than they would have been in a cooler world.

“Human-induced climate change increased the intensity of the extreme rainfall by about 40%,” climatologist Izidine Pinto, one of the study’s authors, said in a briefing. He described the resulting inundation as the worst flooding Mozambique has seen in roughly 25 years.

The study also examined the role of the Pacific Ocean’s La Niña phase, which tends to bring wetter conditions to much of southern Africa. The current La Niña is considered weak, but the team estimated it made the extreme 10-day rainfall about five times more likely and increased its intensity by around 22%.

The scientists cautioned that regional climate models have difficulty reproducing the complex links between La Niña and southern African rainfall. Even so, they said the combination of observational trends and physical understanding gave them high confidence that climate change substantially increased both the likelihood and severity of the rainfall that triggered the floods.

Mozambique at the center of the crisis

Mozambique, a low-lying country at the downstream end of several major river systems, has emerged as the epicenter of the humanitarian emergency.

The World Health Organization’s regional office estimates that about half of the 1.3 million flood-affected people are in Mozambique. The country’s disaster management agency has reported more than 100 deaths since the start of the unusually severe rainy season, including drownings, collapsed homes and lightning strikes. Media reports and local authorities say at least three people were killed in crocodile attacks after floodwaters carried the reptiles into residential areas.

The damage to homes and infrastructure is extensive. More than 70,000 houses have been destroyed and tens of thousands more damaged. Roughly 5,000 kilometers of roads were affected, including long stretches of the main north–south highway, the N1, which was cut in multiple places and left Gaza province temporarily isolated.

Agricultural losses are severe. Government and humanitarian assessments indicate that over 100,000 hectares of crops and tens of thousands of livestock have been lost, wiping out entire planting seasons for many small-scale farmers. The floods come on the heels of recent droughts, raising fears of deeper food insecurity this year.

Hospitals and clinics have also been damaged or left inaccessible. Health officials warn that interruptions to HIV and tuberculosis treatment, maternal and newborn care, and child immunization could have lasting consequences in a country with high rates of infectious disease.

South Africa, Zimbabwe and Eswatini count the cost

Across the border in South Africa, sustained summer rains pounded Limpopo, Mpumalanga, KwaZulu-Natal, the Eastern Cape and North West provinces. Dozens of people were killed after houses collapsed, vehicles were swept away and communities along rivers were inundated.

On Jan. 17, the National Disaster Management Centre classified the floods and severe weather as a national disaster, a formal step under South Africa’s Disaster Management Act that allows the national government to coordinate the response and unlock additional funding.

During a visit to hard-hit areas of Limpopo, President Cyril Ramaphosa noted that some districts had received about 400 millimeters of rain in less than a week. He described clusters of homes as having been “wiped away from the face of the earth.”

In and around Kruger National Park, one of Africa’s flagship conservation areas and a major tourism draw, floodwaters washed out roads and damaged bridges, forcing the evacuation of more than 600 tourists and staff. Park officials have estimated repair costs in the hundreds of millions of rand.

Zimbabwe’s Civil Protection Unit has reported at least 70 flood-related deaths since the start of January, with Masvingo, Manicaland, Midlands and Mashonaland East provinces among the worst affected. More than 1,000 homes have been destroyed, along with schools, roads and bridges. The destruction is expected to further strain a population already facing economic hardship and recurring food shortages.

Eswatini, a small, landlocked kingdom, has seen serious flooding along the Umbeluzi, Incomati and other shared river basins. Detailed tallies are still emerging, but officials say poor housing quality and limited infrastructure have amplified the damage in both rural communities and urban informal settlements.

A brewing health emergency

As floodwaters linger in low-lying areas and temporary shelters remain crowded, health agencies are warning of a second phase of the crisis.

“The floods have disrupted health services and contaminated water systems, putting millions at risk of disease,” Dr. Mohamed Janabi, the World Health Organization’s regional director for Africa, said in a statement. He said WHO is working with governments to prevent disease outbreaks and maintain essential care, with a particular focus on vulnerable groups.

The most immediate concern is acute watery diarrhea and cholera. Mozambique was already battling cholera in northern and central provinces before the latest floods. While no cholera cases had been confirmed in the newly flooded southern areas as of late January, surveillance has been stepped up and supplies pre-positioned.

Stagnant water and debris also create favorable conditions for mosquitoes, raising the risk of malaria in coming weeks. At the same time, damaged roads and bridges have slowed deliveries of antiretroviral drugs, TB medications and vaccines to remote areas.

Exposure, poverty and planning gaps

Beyond the meteorology, experts say the disaster reflects how exposure and vulnerability shape who gets hit hardest.

Large numbers of people in the affected countries live in informal settlements or farm along riverbanks and floodplains, often because safer land is too expensive or already occupied. Houses in these areas are frequently built with weak materials and limited drainage, leaving them prone to collapse or inundation.

In Mozambique’s lower Limpopo basin, researchers and aid groups have documented families being displaced repeatedly by floods over the past two decades, including during the devastating 2000 floods and after Cyclone Idai in 2019.

The World Weather Attribution study noted that recurrent flooding has “trapped rural communities in a cycle of poverty,” as homes, crops and livestock are lost again and again. In many cases, residents rebuild on the same vulnerable sites, lacking the money or political backing to relocate.

In South Africa, the South African Local Government Association said the latest floods, along with recent wildfires in other provinces, revealed that municipal disaster management systems are “buckling” under the pressure of more frequent and severe climate-related events. The organization called for urgent modernization of early warning systems, land-use planning and infrastructure maintenance.

A test case for climate resilience and fairness

The floods have also revived debates over climate justice. African countries collectively account for only a small share of global greenhouse gas emissions, yet are repeatedly among the hardest hit by climate-linked disasters.

Regional officials and scientists say the southern Africa floods underscore the need for increased international funding to help vulnerable countries adapt—by strengthening river defenses, upgrading drainage, relocating the most exposed communities, and reinforcing health and water systems—as well as to compensate for “loss and damage” when adaptation is no longer enough.

The World Weather Attribution team stressed that better climate data and models tailored to African conditions are also vital. Many of the tools used to analyze extreme events were developed in Europe or North America and do not fully capture regional climate dynamics such as the influence of the Indian Ocean or local land-use changes.

For families along the Limpopo, Save and Buzi rivers, those global debates feel distant. In Xai-Xai, residents picked through the mud where living rooms used to be, salvaging cooking pots and schoolbooks and trying to dry them in weak sun.

Some said they hoped to move to higher ground if offered land and assistance. Others said they would rebuild in place, as they did after past floods, because they had no alternative.

“We don’t know when the next big rain will come,” the Mozambican resident at the school shelter said. “We only know that we cannot start again if we lose everything one more time.”