Muswell Hill has very little risk from rivers or the sea, and a real risk from heavy rain. Hardly any of its postcodes fall in a river flood zone. More than a quarter carry a high rating once surface water is counted. There is no recorded flood here. On this hill the flood risk comes from the sky.
On the Environment Agency's river-and-sea flood zones, Muswell Hill barely appears. About 0.2% of its postcodes fall in zone 2, the medium-probability fringe, and none fall in zone 3, the highest-probability band. Counted property by property, the Environment Agency lists one home at medium risk from rivers and sea and two at low risk, and none at high risk. The River Moselle has its source on this hill and in Highgate, and a river at its source has little water to send anywhere.
Surface water is the part that counts. When a heavy downpour arrives faster than the drains can take it, the water runs along the roads and collects in the low points, wherever those happen to be. A hill does not escape that, because the rain falling on the top has to run down somewhere. The postcode figures below show how widely that reaches across Muswell Hill.
Allowing for climate change, the Environment Agency's adjusted river-and-sea flood zone takes in about 0.2% of postcodes, the same share as today. On the river side, the extra rainfall the projections allow for makes no measurable difference to Muswell Hill.
For insurance, river and sea risk at these levels is unlikely to bother an underwriter. Insurers rate the exact address, including its surface water risk, so two houses on one road can be quoted quite differently. Put the specific address into the Environment Agency's long-term flood risk checker and look at the surface water result in particular, because that is the result insurers price on this hill.
Postcode by postcode, counting rivers, sea and surface water together, about 27% of Muswell Hill's postcodes rate high on at least one of those measures. About 20% rate medium on at least one and about 30% low on at least one. A postcode counts if any single measure reaches the rating, and surface water drives almost all of it here.
The Environment Agency's modelled flood extents put none of Muswell Hill's postcodes in the high-probability area, either with defences or without them. About 0.2% fall in the low-probability undefended extent. With so little modelled river flooding, there is almost nothing for a flood wall to hold back. The surface water risk above sits outside these extents, and walls do nothing about it.
The nearest tide gauge to Muswell Hill is at Portsmouth, where the sea rose by about 2 millimetres a year between 1962 and 2023. That rate describes the south coast, which is a long way from a hill in north London. Sea level is not one of Muswell Hill's flood risks.
There is no recorded flood within the area, and that is good news for a buyer. It does not prove a street has never had water across it after a summer storm, because that kind of flooding tends to go unrecorded.
Muswell Hill's flood risk is below average. It is close to nil from rivers and the sea, but a large share of its postcodes carry a surface water rating that a buyer and an insurer will both want to check address by address.