Map · Updated 2026-10-21

Nairobi flood map: where rain water goes

See where rain water runs and collects across Nairobi, street by street and hour by hour. Set a storm — 50 mm in three hours, or more — or run the next three days of forecast rain, and watch the water spread, stand and drain away. Then check any spot: how deep the water got, for how long, and which roads went under.

Open the flood map The next three days Raise the rivers

What the map shows

Water, by depth — pale blue in a film, mid blue at 25 cm, deep blue from a metre. Damp ground under 2 cm is not drawn.
The 10 cm edge — a fine pale line where the water is 10 cm deep: about the depth that comes in under a door.
Where it flooded earlier — a pale hatch where the water stood 10 cm or more at an earlier hour and has drained since.
Roads under water — red where a named road is under 10 cm or more, deep red from 30 cm, about where most cars stop.
Rivers out of their banks — a river is drawn only where it has risen over the land beside it.
The figures — how much of the county is under 10 cm or more, the rain falling that hour, how far the rivers have risen, and the peak so far.

Rivers rise: how high above its river a place stands

Choose Rivers rise and drag the strip: every river goes up together, from half a metre to 10 m over its banks, and the map shows the land each one reaches. It works from one figure for every 60 m square — how high its ground stands above the banks of the river it drains to, following the ground down to that river. A hollow counts from its lip, so water reaches it only by topping the lip.

It is not one water level for the whole city. Nairobi’s ground falls about 470 m from west to east, so a single level would put the east under water and leave the rest dry. Measuring from each place’s own river shows the low ground along every valley at once.

Nairobi’s elevation

The ground model under the flood map gives the height of every 60 m square. Nairobi County’s land lies between about 1,460 m above sea level, at its eastern edge where the Nairobi River leaves the county, and about 1,930 m at its western edge. Half of it is below about 1,630 m, and the city centre stands at about 1,670 m. Check a spot to see the height of any place, how it compares with the rest of Nairobi, and how high it stands above its river.

In 3D

On the Platinum plan the flood map also works in the 3D view: the water lies on the hills and valleys, the roads under it are drawn in red, and you can play a storm or raise the rivers and check a spot there too.

Check a spot

Press Check a spot and tap the map. A card shows the water there now, in centimetres and in words, its highest and when, how many hours it stood 10 cm or more, how high the ground is and how it compares with the rest of Nairobi, the nearest river, and any major road under water within 300 m. Copy link shares the storm and the spot.

Water	The card says
Under 5 cm	Wet ground
5–15 cm	Ankle deep
15–35 cm	Shin deep
35–60 cm	Knee deep
60–90 cm	Thigh deep
90–120 cm	Waist deep
120 cm or more	Chest deep or more

How it works

The ground. The height of the ground every 30 m, from the Copernicus GLO-30 model, with roofs and trees taken out, on 60 m squares over the county and a kilometre round it. The rivers, streams and drains on the map’s Rivers layer are cut into it, and lakes and reservoirs laid flat.
The rain. A storm you set — how much, over how many hours, heaviest near the start as a downpour is — or the next three days of Open-Meteo’s forecast.
Every two minutes. Each square takes its rain, loses a little that soaks in or runs into drains (4 mm an hour unless you change it), and passes water to each lower neighbour: a fifth of the difference in their water levels. Water that reaches a river is carried away.
The rivers. Each river rises with the rain on the land behind it — faster for a small stream, slower and higher for the Nairobi River — and where it rises above its banks, it spills onto the land beside it.
The picture. The water in every square, hour by hour, drawn on the map and played back, with the roads under it.

It runs in your browser, in a few seconds an hour of storm, and the figures fill in as it goes.

What it is not

Not a measurement. The depths are a model’s, on 60 m squares. They show the pattern — where water goes and stands — not the depth at a particular door.
Not an official flood-risk map. It cannot tell you a plot is safe, and it marks no plot or area as a flood zone.
No drains or culverts. They are not in any open data for Nairobi; a blocked drain floods where the map is dry, and a large culvert drains where the map holds water.
Rivers by a rule. No Nairobi river gauge publishes open data, so how far a river rises is set by us from the land behind it, not read from a gauge.
Surface data. The ground model is 30 m, cleaned of roofs and trees; a wall, a raised road or a new building it does not know changes where water goes.

Before you buy or build

Look at a plot in a heavy storm on the flood map, then check the rivers and water bodies near it, and the land’s survey. A plot that collects water in the model is a reason to look harder on the ground — and to ask the seller, the neighbours and a surveyor — not a verdict. Every other check is in built-environment due diligence in Nairobi.

Questions

What is the elevation of Nairobi?

Nairobi County’s land lies between about 1,460 m above sea level, at its eastern edge where the Nairobi River leaves the county, and about 1,930 m at its western edge. Half of it is below about 1,630 m, and the city centre stands at about 1,670 m. Check a spot on the flood map to see the height of any place.

How high above the river is my plot?

Check the spot on the flood map: its card says how many metres the ground stands above the banks of the river it drains to. “Rivers rise” then shows the land each river reaches at a given height over its banks.

Which parts of Nairobi collect water in heavy rain?

In the model, water collects on low, flat ground: along the river valleys, and on the flat land east and south-east of the city centre. The ridges to the west shed it. Search your street on the flood map and play a storm to see it there, hour by hour.

Is my plot in a flood zone?

The flood map does not mark flood zones. It shows where rain water runs and stands in a model built from public data. Use it to ask the right questions about a plot — then look at the rivers near it, and ask a surveyor or an engineer before you buy or build.

Can I see what the coming days’ rain will do?

Yes. Choose “The forecast”: the model runs the next three days of Open-Meteo’s forecast rain over Nairobi, the same forecast the map’s Weather layer shows.

Why does the flood map not replay the April 2024 floods?

Because the rain records it would need are too low. Weather models archive the rain on squares about 9 km across, and for the Mathare floods of 23–24 April 2024 they hold 8 to 14 mm a day — far less than the storm that fell. A replay on that rain would show a dry city.

Why does a river in my storm stay in its channel?

A river rises with the rain on the land behind it, by a rule set by us. Rivers whose land lies mostly outside the county, such as the Mathare and the Gitathuru, which rise in Kiambu, rise less in the model than they may in a real storm. Raise “How fast rivers rise” in the flood map’s Settings to see what a higher river does.

Do I need an account?

No. Anyone can open the flood map, signed in or not.

Where the data comes from

Ground: Copernicus GLO-30 (© DLR e.V. 2010–2014, © Airbus Defence and Space GmbH 2014–2018, provided under COPERNICUS by the European Union and ESA), through Mapterhorn.
Roads: the map’s Major roads layer.
Forecast rain: Open-Meteo.

The flood map is a model on public data, to help you look before you buy or build. It is not a measurement, an official flood map or professional advice.