Which streets bake in summer?
On a hot afternoon, some blocks run several degrees warmer than the rest of town. Asphalt, flat roofs, car parks and industrial land soak up the sun; parks, gardens and water stay cool. We measure that gap for a single postcode from Landsat satellite surface temperature — across 34 UK cities — and show whether an address sits in the hotter or cooler part of its town.
Check a UK postcode → Compare two postcodes
How we read it
summer land-surface temperature (Landsat, ~150 m) → this block minus the town average → percentile of the town
Several clear summer days are composited so a single hot afternoon doesn't skew it. Daytime surface heat — an indicator of the built environment, not air temperature, overnight heat, or a health measure.
What is the urban heat island effect?
Cities are hotter than the countryside around them because hard, dark surfaces — asphalt, concrete, roofs, car parks — absorb the sun and re-radiate heat, while vegetation and water cool the air by evaporating moisture. The gap can reach several degrees, and it varies street by street: a leafy avenue and a treeless industrial estate a few hundred metres apart can differ markedly on the same afternoon.
How do you measure heat for a single postcode?
We read land-surface temperature from the Landsat satellites (NASA/USGS), which carry a thermal-infrared sensor at ~100 m resolution. We composite several cloud-free summer scenes onto a ~150 m grid for each covered city, then show where a postcode sits as a difference from the town average and as a percentile — hotter than N% of the town. The satellite passes at about 10:50 in the morning, so it captures how hot surfaces get in the daytime sun.
Is this the temperature I would feel, or my indoor temperature?
No — and we are careful to say so. This is land-SURFACE (skin) temperature: how hot the ground, roads and roofs get, not the air temperature you feel at head height and not your indoor or overnight temperature. It is a relative indicator of which parts of a town are heat-exposed by their built environment. It is not a heat-health measurement and not a promise about any individual building, which depends on insulation, orientation, shading and ventilation.
Why does it matter when buying or renting a home?
Heat is becoming a comfort and running-cost factor in UK homes, which were mostly built to keep heat in, not out. A block that runs hotter in summer means more uncomfortable top-floor flats, higher demand for cooling, and less relief at night in a heatwave. Knowing whether an address sits in the hotter or cooler part of its town is context a listing will never give you — the same way flood risk or air quality is.
Which cities are covered?
Thirty-four GB cities so far: London, Birmingham, Manchester, Leeds, Glasgow, Sheffield, Liverpool, Bristol, Cardiff, Edinburgh, Leicester, Nottingham, Newcastle, Southampton, Coventry, Bradford, Sunderland, Hull, Stoke-on-Trent, Derby, Wolverhampton, Plymouth, Reading, Brighton, Luton, Bournemouth, Middlesbrough, Preston, Milton Keynes, Norwich, Swansea, York, Oxford, Cambridge. Coverage expands as we process more Landsat scenes. Addresses outside a covered city simply do not show the heat row rather than guess — we never fabricate a reading.
Where can I see it for my address?
The urban-heat reading is one section of the £19 Novarly Parcel UK property report, alongside coal-mining risk, flood zone and likelihood, ground stability, radon, air quality, noise, crime, planning, schools, broadband, energy and sales history. Check any GB postcode free first, then unlock the full report.
Covered cities
Sources: Landsat 8/9 Collection 2 Level-2 land-surface temperature (USGS/NASA, public domain), accessed via the Microsoft Planetary Computer; several cloud-free summer scenes per city composited to a ~150 m grid. A relative daytime surface-heat indicator — not air temperature, not overnight heat, not a heat-health assessment. Updated 2026-07-25.
Novarly Parcel · official public data, read properly · parcel.novarly.com