Extreme heat is no longer a future problem. It is becoming part of everyday life in London. The question is no longer whether temperatures above 40°C could happen again. It is whether our city is designed to cope when they do.
This week’s heatwave wasn’t a glimpse of the future. It was another reminder that London’s climate has already changed. As temperatures climbed across southern England, schools closed early, hospitals faced growing pressure, trains slowed to prevent tracks from buckling, and health officials warned people to stay out of the sun. Once again, experts repeated an increasingly familiar message: much of Britain’s infrastructure was built for a cooler climate. That assumption is already being tested.
For many Londoners, climate change can still feel distant or abstract. Heat changes that. It affects whether your child can concentrate in school. Whether an older relative feels safe leaving the house. Whether your train gets you home. Whether your flat cools down enough for you to sleep.
This is no longer simply an environmental story.
It is becoming one of London’s biggest design challenges.
London has always planned carefully for rain, wind and cold. Victorian sewers, brick terraces, Underground stations and public buildings all reflect a city designed around Britain’s historic climate.
Extreme heat was treated as an occasional inconvenience rather than a design requirement.
That assumption is beginning to fail.
Many schools struggle during prolonged hot weather. Older Victorian classrooms can become stifling, while some newer schools with large areas of glazing and lightweight construction can also overheat quickly if they lack effective shading and natural ventilation. Hospital estates face similar challenges, while rail operators regularly impose speed restrictions as steel tracks expand in the heat.
These are not management failures.
They are reminders that much of our infrastructure, whether built decades ago or more recently, was never designed with regular 35°C to 40°C summers in mind.
Perhaps nowhere is the challenge more personal than in our homes.
Many London flats, particularly modern apartments built to retain warmth during winter, become extremely difficult to live in during prolonged hot weather. Upper-floor homes can remain uncomfortably warm throughout the night, giving people little chance to recover before another hot day begins.
Researchers increasingly warn that warm nights may become as significant a health risk as daytime temperatures. Without overnight cooling, the body never properly resets, particularly for older people, babies and those living with existing health conditions.
For years, conversations about housing have focused on keeping heat inside buildings.
The next chapter may be equally concerned with letting heat escape.
That raises important questions.
Should new homes have mandatory external shading?
Should planning policy require cross-ventilation?
Should overheating standards carry the same weight as energy efficiency?
And what happens to the millions of existing homes that were never designed for this climate?
Some newer developments are already pointing the way forward. Increasing attention is being given to external shading, naturally ventilated spaces, roof gardens and planted terraces that cool buildings while also improving biodiversity and wellbeing.
Many of the principles promoted through London’s retrofit agenda, better ventilation, solar shading, green roofs and reducing hard surfaces, turn out to be exactly the same interventions needed to help buildings cope with hotter summers.
Perhaps we should stop thinking of retrofit as simply a net zero programme.
It is becoming a climate adaptation programme too.
Heat is not experienced only inside buildings.
It shapes how people use the city.
A shaded street feels completely different from one lined with dark paving and little tree cover. Parks become places of refuge rather than recreation. Public drinking fountains, benches beneath mature trees and accessible public toilets suddenly become essential infrastructure rather than pleasant extras.
Even simple design decisions matter.
Can you wait comfortably for a bus?
Can children still play safely in a local park?
Can older people walk to the shops without risking heat exhaustion?
These questions rarely feature in debates about urban design.
Perhaps they should.
Fortunately, London is not starting from scratch.
The London Plan already recognises that urban greening is no longer a decorative extra. Policy G5 requires major developments to integrate greenery into the design of buildings and public spaces from the outset, using the Urban Greening Factor to help create healthier, cooler and more climate-resilient neighbourhoods.
The challenge now is one of pace and scale.
Many of London’s newest developments demonstrate what is possible. The transformation of King’s Cross, the public spaces around Coal Drops Yard, the landscape-led neighbourhoods at Wood Wharf and the extensive planting throughout Queen Elizabeth Olympic Park all show how trees, planting and generous public spaces can make dense parts of the city noticeably more comfortable during hot weather.
These places are attractive because they are greener.
Increasingly, they may also prove to be more resilient.
There is no single solution.
Air conditioning will inevitably play a larger role in some buildings, particularly hospitals and care homes. But simply installing more cooling systems risks increasing energy demand and making cities even hotter unless carefully planned.
Fortunately, many of the answers are already well understood.
More street trees.
Better ventilation.
External shading.
Lighter materials that absorb less heat.
Greener roofs.
Buildings designed to cool naturally.
Public spaces that provide shelter rather than intensify heat.
The question is no longer whether these ideas work.
It is whether we can deliver them quickly enough.
The proposed pedestrianisation of Oxford Street has generated plenty of debate about buses, taxis, deliveries and retail.
But perhaps another question deserves equal attention.
Could removing traffic create one of central London’s most comfortable streets during increasingly hot summers?
Not because temperatures fall dramatically, but because wider pavements create opportunities for more trees, planting, seating, shade and places where people actually want to linger.
For decades, London’s streets have largely been designed to move vehicles efficiently.
The next generation may need to protect people just as effectively.
If we are redesigning one of the world’s most famous shopping streets, should we also be designing it for the climate London now has, rather than the one it had fifty years ago?
For many Londoners, this conversation is not new. Hot summers have exposed the city’s vulnerabilities for decades. Yet each heatwave still reveals many of the same weaknesses, from overheating classrooms and homes to pressure on hospitals and disruption to transport.
At The London Society, we often say that the built environment is not abstract. It shapes health, opportunity and everyday life.
Extreme heat demonstrates that more clearly than almost any other issue.
This is not simply about climate policy.
It is about schools that remain usable in June.
Homes that are still comfortable in July.
Hospitals that can continue operating safely.
Transport networks that remain reliable.
Neighbourhoods where older people can still enjoy walking to the park.
As our Chair, Leanne Tritton, observed while reviewing this article:
“Everyone keeps talking about what the future will look like. It’s here. This is what it is like.”
We already know many of the solutions. Urban greening is embedded in the London Plan. Better building design, retrofit and thoughtful public spaces are showing what good looks like across the capital.
The challenge is no longer understanding the problem. It’s adapting London at the speed its changing climate demands.
