The UK Air Con Index: the 91 places that most need home air conditioning
We scored 91 towns and cities in England and Wales on summer heat, overheating-prone housing, and affordability. Southend-on-Sea comes out on top, and the commuter East dominates the top ten.
Southend-on-Sea has a stronger case for home air conditioning than anywhere else in England and Wales. That is the headline finding of the Air Con Index, our ranking of 91 towns and cities by how much they actually need cooling, built from Met Office temperature records, Census housing data, and ONS affordability figures.
Southend scores 91.8 out of 100. It ties with London and Colchester as the hottest place in the ranking, with a mean summer maximum of 23.5°C over the last decade, and more than a third of its homes are flats, the housing type most prone to overheating. Add house prices and ownership levels that make installation a realistic option for more households, and the seaside commuter town becomes, by our measure, the air con capital of the country.
The top ten
| Rank | Place | Score |
|---|---|---|
| 1 | Southend-on-Sea | 91.8 |
| 2 | Watford | 89.0 |
| 3 | London | 88.9 |
| 4 | Cambridge | 86.8 |
| 5 | Slough | 83.3 |
| 6 | Reading | 80.4 |
| 7 | Bristol | 76.5 |
| 8 | Southampton | 76.2 |
| 9 | Chelmsford | 75.8 |
| 10 | Oxford | 75.8 |
The full table of all 91 places, and a separate ranking of London's 33 boroughs, is on the Air Con Index page.
The pattern is hard to miss. Four of the top ten sit in the East of England, and four more in the South East. The commuter belt east and west of London combines the warmest summers in the country with a housing stock full of flats and conversions, which is exactly where working from home through a heatwave is least comfortable. The index suggests the strongest demand for cooling is not scattered across the country; it is concentrated along the commuter corridors.
What the index measures, and what it doesn't
The index is not a list of the hottest places. It scores each town and city on three pillars: summer heat, weighted at 40%, using the mean summer maximum temperature from 2016 to 2025 from the Met Office HadUK-Grid dataset; overheating-prone housing at 30%, using the share of homes that are flats from the 2021 Census; and affordability at 20%, combining median house prices and owner-occupation rates from the ONS. The scores are re-based so the strongest overall case scores towards 100.
In other words, it measures need and realisable demand, not current ownership. A place scores highly when its summers are hot, its homes hold that heat, and enough of its residents own the property and could plausibly pay for installation. The full methodology, including every source and its time period, is on the index page. Coverage is England and Wales; comparable data for Scotland and Northern Ireland is not available at town level.
Inside London, the flats tell the story
London appears once in the national table, in third place, but its 33 boroughs vary so much that we ranked them separately. The City of London tops the borough table with 82.9, where 98% of homes are flats. Westminster follows on 82.3, with 89.7% flats, then Islington, Tower Hamlets, and Hackney. Dense inner-London living concentrates heat in exactly the homes least able to shed it: single-aspect flats with no cross-ventilation and nowhere for warm air to go overnight.
The renters locked out of cooling
The most uncomfortable finding in the data is not about temperature. The boroughs with the greatest overheating risk also have some of the lowest owner-occupation in the country, and renters usually cannot fit a fixed air conditioning unit without their landlord's agreement. Tower Hamlets is the starkest example: fourth on the borough table for overall need, yet only 23.1% of its homes are owner-occupied, giving it an affordability score of just 8.3. The people most likely to swelter in an overheating flat are the least able to do anything permanent about it.
That is why the affordability pillar includes ownership at all. Cooling a home you rent usually means a portable unit or negotiating with a landlord, not a wall-mounted system, and any honest measure of realisable demand has to reflect that.
Least need is not failure
At the other end of the table sit Durham on 15.1, Carlisle on 13.4, Blackburn on 10.3, Sunderland on 10.0, and Hartlepool on 8.8. Their summer maxima run from 18.9°C to 20.5°C, cool enough that most homes manage without mechanical cooling. That is a 4.6°C gap between Sunderland and Southend, a genuine north-south cooling divide, and it means a low score is simply a mild summer, not a place falling behind. If your town is near the bottom of the table, the index is telling you your money is probably better spent elsewhere; our guide to whether air conditioning is worth it starts from exactly that question.
Use the data
If your town is near the top of the table and you are weighing up cooling, start with what it would actually cost: our guide to air conditioning running costs covers the typical figures, and the BTU calculator sizes a unit for your room in under a minute.
The full ranking, the borough table, and the complete methodology are on the Air Con Index page. Data is correct as of July 2026; heat figures are a 2016 to 2025 mean, housing is Census 2021, and house prices are for the year ending March 2023.
Analysis by Aircon Adviser. Free to reproduce with a link to this page.