Living in Nairobi, you feel the rain differently these days. When it pours, and it pours harder and more unpredictably than before, the streets turn into rivers overnight. In Mathare, Kibera, or Kawangware, families wake to water lapping at their doorsteps, or rushing through their homes. Friends and neighbors have lost everything in a single night: furniture floating away, small businesses ruined, children missing weeks of school. This isn’t just bad weather, it’s a growing crisis tied to climate change, hitting informal settlements the hardest and dragging down the city’s, and the country’s, economic momentum.
Nairobi is growing fast. More people stream in from rural areas every year seeking work, swelling the urban population. Over half of the city’s residents live in informal settlements - rows of tightly packed homes made of iron sheets, mud, and concrete blocks, often along rivers or in low-lying areas. These spots were cheap or free because no one else wanted them: flood-prone, close to dump sites, far from proper roads or drainage. But as rainfall patterns shift, those “cheap” locations have become deadly traps.
When the Rains Come
The floods of 2024 are still fresh in memory. Heavy rains from March to May caused rivers like the Nairobi and Athi to overflow. Hundreds died nationwide, and tens of thousands were displaced in Nairobi alone. Informal settlements suffered the worst - homes washed away, sewage mixing with floodwater, spreading diseases like cholera. Reports from the World Resources Institute show that millions living in these areas have little defense against rising waters due to poor construction and inadequate drainage. In Mathare, dense riverside housing became a disaster zone overnight, wiping out livelihoods.
Fast forward to early 2026, and the pattern hasn’t stopped. Flash floods strike even outside the record-breaking events of 2024. In January, sudden downpours clogged already overwhelmed drains. Residents in low-lying zones spent days bailing water, losing stock in small shops, or watching their boda-bodas rust beyond repair. The economic impact is immediate and deep.
The Hidden Economic Cost
The informal sector drives much of Kenya's urban economy: street vendors, small traders, mechanics, hairdressers. When floods strike, these businesses shut down. Goods spoil, customers can't reach them, and transport costs skyrocket because roads become impassable. A World Resources Institute analysis notes that informal employment makes up 50–80% of jobs in cities across the Global South. In Nairobi, when floods strike Mathare or Kibera, the ripple spreads far - families can’t pay rent, children drop out of school to help at home, and health issues rise from contaminated water. One study estimates floods cost Kenya roughly 5.5% of GDP every seven years, with urban areas taking the largest share.
Women and children suffer most. In informal settlements, women often run home-based businesses or care for families. Floods force them to wade through contaminated water to fetch supplies, increasing risks of illness or gender-based violence. Children miss school, fall behind, or are drawn into labor to help recover losses. It is a cycle that is hard to break.
The reason it is worsening is clear. Climate change is intensifying extreme weather. Heavier, more intense rainfall events are becoming normal, even as poor planning leaves cities ill-prepared. Nairobi’s drainage systems are outdated, designed decades ago for a much smaller population. Blocked waterways, plastic waste, and construction on wetlands leave water with nowhere to go but into homes. Informal settlements, squeezed into risky spaces, have no buffer.
What Needs to Change
Communities are fighting back. In Kibera, residents plant trees along riverbanks to stabilize soil and use sandbags or rubble to divert water. Projects supported by groups like Cities Alliance and Slum Dwellers International help locals map risks and advocate for better planning. In Mathare, families are greening riverbanks to slow erosion. These grassroots efforts show resilience but they need scaling up with real government support.
Government responses have been piecemeal. After 2024, authorities announced relocations and tried to enforce riparian buffer zones. Without proper compensation or resettlement, many returned to the same risky areas. The National Climate Change Action Plan prioritizes flood control in informal settlements and early warning systems, yet implementation lags - funds stall, corruption creeps in, and action is too slow.
The economic threat is real. Nairobi contributes heavily to Kenya’s GDP through services, tech hubs, and manufacturing. Repeated floods disrupt supply chains, damage roads and power lines, and deter investors seeking stability. Youth unemployment remains high when small businesses cannot recover. If urban vulnerability is not addressed, the country’s growth trajectory will slow - productivity will fall, poverty will rise, and migration pressures will grow.
The solutions are clear: include informal settlement residents in planning, invest in resilient infrastructure - better drains, permeable surfaces, green spaces - enforce building regulations without punishing the poor, and provide affordable housing alternatives. Strengthen community-led adaptation, like app-based networks SEI is testing in Kibera, and push for global support, including debt relief, to free up funds for climate adaptation.
From where I sit in Nairobi, the rain is no longer just weather, it is a warning. Floods keep hitting the most vulnerable first, but the costs ripple across the city. Treating informal settlements as afterthoughts will only make the next disaster more expensive. Those living on the front lines already know it. The question is whether policymakers will listen before the next downpour turns resilience into regret.
Pharis Gichanga
Policy Analyst
