Preparing for a warmer future - heat in the UK

As the planet warms, the UK is waking up to a new health crisis: one measured not just in degrees, but in hospital admissions, respiratory attacks, mental stress, productivity costs and financial strain.

With the Met Office confirming that 2025 was the warmest year on record, these hot days are no longer a novelty, but rather they come as a warning sign. While for some, they might mean more barbecues and trips to the beach, the same warmth brings a forecast of hospital visits, respiratory issues, sleepless nights, and for increasing numbers, life-threatening risks. For a country built for the cold, the UK’s relationship with heat is changing fast. 

The UK’s mean temperature this year reached 16.10°C, the highest on record, pushing 1976 out of the top five hottest summers. But unlike 1976, which was seen as a once-in-a-generation anomaly, today’s heat is part of a global pattern. Every region of the world is now experiencing higher temperatures with nine out of the last ten summers in the UK being above the long-term average. As climate scientist Dr Frederike Otto put it, ‘the fingerprints of climate change’ are all over these intense heatwaves we are witnessing.

Rising greenhouse gas concentrations are trapping heat in the atmosphere, tilting Britain’s climate toward the warmer, drier conditions seen across much of Europe. And as temperatures climb, so too do the health risks. This new climate is reshaping daily life, from how we sleep to how our health systems cope under strain. The consequences are becoming increasingly visible, even when not directly recorded.

Heat is already taking a toll. The Lancet Countdown’s latest report states that one person is killed every minute due to rising global heat. In 2024, England recorded 1,311 heat-related deaths. These figures likely understate the true scale of impact with heat often being known as a ‘silent killer’, aggravating pre-existing conditions rather than being listed as a direct cause of death. 

The London School of Hygiene & Tropical Medicine and Imperial College London found that climate change intensified Europe’s 2025 heatwave, contributing to 16,500 additional deaths across the continent including 1,147 deaths in the UK. In London alone, 315 deaths were linked to extreme heat which is a reminder that there aren’t just continental statistics, but realities playing out at home. 

Hotter summers mean higher mortality. During the 2022 heatwave, the UK Health Security Agency (UK HSA) estimated around 2,985 excess deaths  linked to extreme heat. While the final UK HSA figures of 2025 are yet to be confirmed, the pattern is consistent, extreme heat continues to claim lives, particularly among the elderly, young children, and people with long-term conditions.

Researchers warn that even at 1.6°C of warming, the annual number of heat-related deaths will increase by up to sixfold. Without the emissions reductions delivered since the 2015 Paris Agreement, projections show deaths could have increased more than fifty-fold under a 4.3°C warming. The Paris framework has already helped slow the pace of warming from a slowdown in emissions. Sustained cooperation will determine whether the UK continues to face a rise in heat-related deaths or an avoidable public-health crisis.

For those with respiratory conditions, hotter weather brings greater difficulty often in the form of wheezing and breathlessness. Warm, stagnant air traps pollutants close to the ground, worsening air quality. Meanwhile, higher temperatures not only extend the pollen season, but intensify it, further aggravating asthma and hay fever symptoms.

Around 7.2 million people in the UK live with asthma, and each summer, hospital admissions spike as the heat combines with air pollution and allergens. Urban areas such as London suffer more due to the ‘urban heat island’ effect, where concrete and traffic make cities several degrees warmer than surrounding areas. During last year’s heatwave, air pollution in London spiked to ‘very high’ levels prompting warnings for people with asthma and heart conditions to stay indoors. As someone living with asthma in London, during those heat spikes, even simple errands can begin to feel physically demanding. 

These trends are not abstract. What do they result in? More inhalers, disrupted sleep, missed days of work or school and increased visits to the doctors. 

Heat does not only affect the physical body, but it weighs hot on the head too. Research suggests that mental health deteriorates during periods of prolonged heat, with stress, anxiety and sleep disruption all increasing. The UK Health Security Agency notes that people taking certain medication, including antidepressants or antipsychotic, can be especially vulnerable as these interfere with the body’s ability to regulate temperature.

Parents and children are also feeling the strain. A recent study found that over five million children in England live in homes at risk of overheating, but this burden is placed heavily on those in social housing, with one million at risk in London alone. Poor ventilation and rising indoor temperatures create conditions that make rest and recovery difficult during heatwaves that now stretch for weeks rather than days. Parents often find themselves struggling to comfort overheated infants while juggling work, creating both emotional and financial strain.

Hotter summers ripple through workforces. Outdoor labourers from construction workers to farmhands face increased risk of dehydration and heat stress. As one report notes, around a quarter of UK workers are employed in occupations vulnerable to heat exposure with the consequences extending beyond health to reduced productivity, as well as economic losses.

The UK Climate Risk Assessment estimates that heat-related mortality, lost productivity and health treatment cost £6.8 billion annually in the 2020s, rising to £14 billion by mid-century.  These impacts don’t stop at home, in hospitals, or on farms, but they extend into our supermarket shelves. Farmers face disrupted harvests as heat and drought damage crops, threatening livelihoods and food security. ECIU analysis shows the UK experienced one of its worst harvests in a decade driven by prolonged heat and drought. As local yields continue to decline, the UK becomes dependent on food imports from countries also struggling with heat stress and water scarcity with around 15% of the food we import coming from countries most vulnerable to climate change. This creates a feedback loop where climate impacts abroad directly shape prices and availability at home, linking health, labour, and food security in more complex ways.

The financial toll of climate change is rising as fast as the temperature. Lost productivity, health pressures and infrastructure disruption are already affecting households and businesses. As the climate warms, these costs risk outpacing adaptation, affecting not just public health, but overall economic stability.

Recognising the growing health burden of heat, the UK has already introduced measures such as the Heatwave Plan for England which has evolved into the Adverse Weather and Health Plan, alongside UKHSA heat alerts. These frameworks aim to better prepare both healthcare systems and the public for extreme weather.

Yet adaptation still lags behind reality. With much of Britain’s housing stock being poorly adapted to hotter conditions, around one in five homes currently overheat during summer, and more than half of low-income families live in properties particularly prone to dangerous indoor temperatures. Experts and the Environmental Audit Committee advise that adaptation will require a mix of stronger building standards, retrofitting older homes to reduce overheating, expanding green and blue spaces in urban areas, and improving public awareness of heat-related risks.  

Tackling air pollution and reducing emissions remain critical for improving public health in the long term, which serves as a reminder that the same policies that protect the planet also protect future generations by reducing the physical, mental and financial toll of extreme heat.