St John's Wood is out of reach of rivers and the sea, and its flood risk comes from above. None of its postcodes fall in the river-and-sea flood zones. Roughly one in eight still flags high risk on at least one measure. That is rainwater, hard paving and a road surface with nowhere to send it. The threat here is a downpour, and the tide does not come into it.
The Environment Agency's river-and-sea mapping puts 0% of St John's Wood's postcodes in Flood Zone 3, the highest-probability band, and 0% in Flood Zone 2, the medium-probability fringe beyond it. On the official maps, rain stopping play at Lord's is the closest the district comes to a water problem.
Surface water is the part that counts. When heavy rain falls faster than the ground and the gullies can take it, water collects in the low points of the street and in anything built below them. It is the only kind of flooding that registers in St John's Wood, and it does not need a river to happen.
The forward look is just as clean for rivers and sea. The Environment Agency's climate-adjusted zone, which allows for a wetter future, takes in 0% of the district's postcodes. That allowance covers rivers and sea, so it leaves the rainwater question exactly where it was.
For insurance, a district with no river or sea exposure usually gets a quieter conversation with the underwriter, though a surface-water flag on a particular postcode can still change the quote. Get a buildings insurance quote on the exact address while the sale is still being negotiated, since the insurer prices the postcode and the floor level, and the district average comes into neither.
The postcode-level picture folds surface water in alongside rivers and sea and counts a postcode if any one of those measures flags it. On that basis about 12% of St John's Wood's postcodes rate high on at least one measure, about 9% medium and about 16% low. Those are the shares to read if you want to know how often rain is the problem, and the river-and-sea zones above are a separate question.
Defences hardly come into it. The Environment Agency's modelled flood extents put 0% of postcodes in a high-risk area without defences and 0% in one with defences present. A defence on the model only means one exists, and here there is nothing in the model for one to hold back.
The nearest tide gauge in the record is at Portsmouth, where the sea rose by about 2 millimetres a year between 1962 and 2023. That measurement belongs to the south coast, which is about as far as the sea gets from this question.
No historic flooding is recorded across St John's Wood's postcodes. That is a fair comfort, though an empty record means nothing was logged, and a flooded basement on one street rarely makes it into a national register.
St John's Wood's flood risk is middling and comes almost entirely from rain, with rivers and the sea well out of the picture. The buyers who need to check are the ones looking at a property on a postcode with a surface-water flag.