‘It can kill us’: Kenyans brace for an El Niño the forecasters call historic

A wall of corrugated iron, and a flood line halfway up it

“It flooded up to here in March,” Agnes Shikoli says, pointing halfway up the six-foot corrugated iron wall of her home in Kibera, one of the largest informal settlements in Kenya. Her house stands a couple of metres from the Ngong river, which runs through densely populated Nairobi.

The marks of the long rains are still visible; a broken television in the corner, immersed when the river rose. Tucked out of sight is a photograph of her sister Beatrice Khalayi, 58, who died when the intense rains ravaged Kibera, among more than 60 people who lost their lives.

“Someone called me to tell me that she had died of electrocution after her house flooded,” Shikoli recalls. With the short rainy season now starting, she is afraid; above all after warnings that El Niño could bring a new round of flooding. “I feel like it can kill us. These houses aren’t made of stone,” the 62-year-old says. “They can fall on us, or the water can drown us.”

Shikoli makes about $2 a day selling groundnuts and fruit from a stall beside the river. Officials have told her family to leave their riverbank home until the rains pass; advice that is hard to follow when the stall, and the income, sit beside the water.

The numbers behind the warning

A regional outlook from the Intergovernmental Authority on Development warned in September of an 81% probability of a very strong El Niño during October to December 2026, with a 97% probability it continues into March to May 2027. It came from the IGAD Climate Prediction and Applications Centre after a climate forum in Kigali in mid-August.

The World Meteorological Organization warned in October that the current event could be unprecedented in strength, with Pacific sea temperatures rising as much as 3.8 degrees Celsius above average between November 2026 and January 2027, and the event expected to peak towards the end of 2026.

In East Africa, the Pacific warming is reinforced by a second driver: a positive Indian Ocean dipole, which warms the western Indian Ocean and pushes more moisture over the Horn. Forecaster Jemima Gacheru told the BBC that Indian Ocean temperatures now resemble those of 1997, the El Niño this season is most often compared with.

Kenya’s own meteorological authority expects above-average rainfall across about 80% of the country during the October to December short rains. Its Nairobi forecast puts the peak in November, with cumulative rain above 550mm in Westlands, Dagoretti and Kibra, and the rains continuing into January 2027. The regional outlook puts the chance of above-normal rain above 90% in north-eastern Kenya, with more than 400mm expected in parts of central Kenya. The same phenomenon is expected to bring the opposite problem to southern Africa, where the rains are forecast to fail rather than flood.

What the forecast cannot say yet

Nobody knows exactly when the rains will come; or how much rain there will be. So far, the heavy rains predicted have not occurred, and forecasters stress that a strong El Niño does not automatically mean flooding everywhere: outcomes vary from one county to the next, and even between neighbouring communities.

It is also unclear whether this event will match the scale of 1997–98, when floods killed 2,000 people in Somalia and forced a further 250,000 to flee, according to the Food and Agriculture Organization. The comparison is widely made, but the forecast covers large areas and a whole three-month season.

What is not known, finally, is whether the money and the orders will arrive in time. Nairobi needs up to $192 million to upgrade its drainage entirely, and there is little sign that either the national government or the city council can raise it. Whether families told to leave the riverbanks will actually go, and where they will go, is still open.

The drainage was built for a city half this size

Nairobi’s drainage was not built for the city it now serves. The system was developed 30 years ago for about 2.5 million residents; Nairobi now holds about 7 million people in the daytime and 5.5 million at night, according to the county’s disaster chief, Bramwell Simiyu. Blocked drains and inadequate sewage were widely blamed for the high death toll after the floods earlier this year, when excess rainfall had nowhere to escape.

The county has mapped 20,000 households across four flood corridors. Moderate projections put about 5,000 households, or 20,000 people, at risk; in the worst case, about 100,000 people would need evacuation and shelter, and the county has designated 167 holding grounds where relief food and supplies would be distributed.

The Kenya Red Cross says more than two million people could be affected across 46 of the country’s 47 counties. The UN’s migration body, the International Organization for Migration, has warned that almost 900,000 people could be forced from their homes in Kenya this year, mostly by the predicted floods. In neighbouring Somalia, the disaster agency has warned that 1.2 million people are at risk of displacement. A September assessment put about 2.1 million Kenyans in high acute food insecurity between November 2026 and January 2027, with El Niño floods expected to make it worse. The strain comes as foreign aid to Africa has fallen sharply, with Kenya among the countries hit hardest.

Probability is not a prediction, and that is the point

An 81% probability of a very strong El Niño is not a promise of floods. It is a statement about the odds over a whole season and region. Even as flood warnings stand, Nairobi Water cut production by 35% on 9 November after below-average rainfall left the Ndakaini Dam low; a reminder that the rains so far have been lighter than forecast, not heavier.

That gap between forecast and arrival is where the danger sits. The 1997–98 comparison is real, Indian Ocean temperatures then and now are similar, and the two drivers, Pacific warming and a positive dipole, are aligned again, but analogues are not destinies. What turned the March rains deadly was not the volume of water alone; it was drains untouched for years, settlements pressed against rivers, and a drainage system built for a city half the current size. The same combination is still in place, which is why the same rain would do the same damage.

The deeper story is the one the Nairobi River Basin Regeneration programme already wrote: settlements near rivers, weak enforcement of planning rules, and rising poverty pushing people towards the water; and its recommendation of river buffers and humane relocation remains largely unbuilt.

What the rains set in motion beyond Nairobi

The second-order effects start with movement. The UN refugee agency warned on 5 November that up to three million people could be displaced by severe flooding across Kenya, Somalia, South Sudan and Uganda by the end of 2026, in a report released days before the COP31 climate summit opened in Antalya, Turkey, on 9 November. Displacement on that scale would strain neighbours already hosting refugees, and it would arrive where parts of Somalia are already in the middle of a devastating drought; flood and drought, side by side, in the same season. Heavy rains have already flooded displacement camps elsewhere this year, a preview of what the Horn could face.

Then come the markets. Flooded roads cut access to schools, hospitals and markets; damaged crops push food prices up; standing water brings disease. The same season that threatens Nairobi’s riverbanks threatens harvests across the Horn, and Kenya’s food-security outlook already counts about 2.1 million people in high acute food insecurity through January. A strong El Niño also reaches beyond Africa: the WMO warns of severe drought in some regions and heavy rainfall in others, long after its late-2026 peak.

For the region, the season is also a rehearsal. The Horn has faced major El Niño flooding in 1997–98, in 2023–24 and again in the March rains of this year. Each time, the post-mortem names the same causes. Whether this season breaks that pattern will be decided less by the Pacific than by what was done between warnings.

November is the month to watch

November is usually the peak month of the short rainy season, and it is the month the forecasts point to. Kenya’s meteorological department and the counties are expected to issue detailed warnings as the season develops, and Nairobi’s multi-agency command centre is already activated. Four things will decide what happens next: the strength of the rains, whether the four flood corridors hold or flood, whether families on the riverbanks follow the order to leave, and whether the holding grounds and relief stocks are ready. The Climate Worx river clean-up, intensified since August, continues in the meantime; shovels and rakes against a forecast.