Suburban Area CLIMATE RISK

Mortlake Flood Risk Data

Mortlake sits inside the Richmond upon Thames council area, in Greater London, made up of residential streets and local-centre parades rather than its own town centre. LocalRisk has flood, heat, air and ground-stability data for 369 postcodes in Mortlake; 12 samples are linked at the foot of this page.

20.1% of postcodes in Mortlake fall into the Environment Agency's high flood-risk band - well above the UK average of about 7%. A further 15.2% sit in the medium band; 64.7% are lower-risk. Across the wider Richmond upon Thames council area the figure is 13.0%, so Mortlake runs higher than its parent council. Two postcodes a few streets apart can land in different bands; what drives the gap is elevation, distance to the nearest watercourse, and how the surrounding drainage performs in heavy rain. The postcode list at the foot of this page links to the full address-level reading for each postcode in Mortlake.

Met Office UKCP18 projections estimate around 40 days above 25°C per year across the Richmond upon Thames area for the 2021-2040 period - the central scenario under high emissions; lower-emissions paths give lower numbers. Heat exposure within Mortlake itself is uneven: top-floor flats, west-facing terraces and properties without through-ventilation hold heat well into the night, while ground-floor homes near tree cover or open ground cool faster. The headline 40-day figure is an area average, not a property-level reading.

Annual mean PM2.5 across the Richmond upon Thames area is 8.3 µg/m³ - above the World Health Organisation guideline of 5 µg/m³ and within the UK Environment Act 2021 target of 10 µg/m³ by 2040. Within Mortlake, readings are not flat: postcodes within 200 metres of an A-road or major junction routinely run 30-50% higher during weekday rush hours than residential streets two roads back. Defra's UK-AIR network supplies the underlying figure.

Ground stability in Mortlake follows the underlying geology more than the postal boundary. The British Geological Survey GeoSure dataset maps clay shrink-swell risk on a 50-metre cell, and properties on the same street can sit in different bands where a clay seam ends mid-road. Pre-1980 housing on clay-rich ground is the most exposed; properties on bedrock or well-drained sandy soils are typically lower-risk. A postcode-level check picks up that variation.

A free postcode check on LocalRisk covers up to six hazards for any address in Mortlake: Environment Agency flood mapping, BGS ground stability, Met Office heat projections, Defra PM2.5, plus coastal erosion and green-space access where relevant. The postcode list below opens an address-level report for each postcode in Mortlake; the council link at the top of this page returns to the wider Richmond upon Thames picture.