# More Than 2,700 Estimated Deaths Linked to May and June Heatwaves in England and Wales
## A Deadly Start to Summer
England and Wales endured two exceptional heatwaves in May and June, and the human cost may have been staggering. Researchers from Imperial College London, the Met Office, and the London School of Hygiene and Tropical Medicine estimate that more than 2,700 people may have died from heat-related causes during the two events combined.
The figure is an estimate, not a confirmed death count. It is derived from statistical modelling that uses historical death records and established knowledge about how extreme heat affects mortality. The researchers are transparent about the limitations of this approach — the findings rest on assumptions about how severely people were affected, and reality may differ. But even allowing for uncertainty, the numbers are sobering.
The team broke the estimate into two windows. Between 21 and 29 May, roughly 550 people are thought to have died as a result of the heat. Between 18 and 28 June, nearly 2,200 deaths are attributed to the second, more severe heatwave. The June event, they note, accounts for the majority of the estimated deaths.
## Record-Breaking Temperatures
Both months saw temperatures that rewrote the record books. In May, the UK hit a new high of 35.1C at Kew Gardens on 26 May — a striking jump from the previous May record of 32.8C, which had stood since 1922 and was equalled in 1944. That is a full century of history surpassed in a single afternoon.
June was even more remarkable. It was the warmest June on record in England, with temperatures reaching 37.7C (99.9F) at Lingwood in Norfolk. That figure smashed the previous June high of 35.6C, a record set in 1957. During the peak of the event, the Met Office issued a rare red heat alert for parts of England and Wales, warning that even healthy people faced a significant risk to life.
## What Caused the Heatwaves?
Both heatwaves were driven by what meteorologists call a “heat dome” — a stalled area of high pressure that traps hot air over a region, allowing it to build and persist day after day. The phenomenon is well understood, but what made these events particularly extreme was the backdrop against which they occurred.
The researchers say human-induced climate change has warmed the planet by approximately 1.4C since pre-industrial times. They estimate that this warming added between 3 and 4C to the maximum temperatures recorded during the May and June heatwaves. In other words, without the additional warming driven by greenhouse gas emissions, the peaks would still have been hot — but not record-shattering.
Hot tropical nights compounded the danger. When temperatures fail to drop significantly overnight, the body gets no respite. This matters more than many people realise, because the physiological strain of heat is cumulative. Prolonged exposure without overnight recovery is far more dangerous than a brief daytime spike.
## Why Heat Kills
Heat places immense physical strain on the body. The heart pumps harder and faster in an attempt to cool the body down, redirecting blood to the skin. If a person is dehydrated, this strain intensifies. The consequences can include heart attacks, strokes, and other potentially fatal medical emergencies.
Certain groups are more vulnerable. Babies and older people are at heightened risk, as are individuals with pre-existing health conditions. But the researchers stress that intense heat can affect anyone, including those who are fit and healthy. Heat is sometimes described as a “silent killer” because the early symptoms — fatigue, dizziness, headache — are easily dismissed or overlooked until the situation becomes critical.
Humidity makes things worse. When the air is very wet, as it was during the June heatwave, sweat evaporates less efficiently. That undermines the body’s primary cooling mechanism, making it harder to regulate internal temperature even when a person is resting in the shade.
## A Personal Tragedy
The statistics, however carefully constructed, can feel abstract. The human reality behind them is not.
Professor Emily Shuckburgh, who serves as chief scientific adviser for the Department for Energy Security and Net Zero, told the BBC’s Today Programme that her father died during the extreme heat last month.
“My own father suffered a stroke,” she said. She acknowledged that they do not know whether it was heat-related, but added: “The ambulance services were overwhelmed and it took a number of hours for him to get to hospital. Really sadly, he didn’t survive.”
“Now, I can’t say that was because of the heat, I am sure the heat didn’t help, but it really underlines the fact that… these extreme heat events are costing lives today, and we really need to take climate change seriously.”
Her account highlights a dimension of heatwaves that mortality models may not fully capture: the strain that extreme weather places on emergency services, and the downstream effect on people who need urgent medical care for any reason, not just heat-related illness.
## A Warning Not to Be Dismissed
Professor Fredi Otto, a climate science expert at Imperial College London who was involved in the research, offered a blunt message: “Don’t underestimate the risks. Just because you’re fit and healthy, you’re not safe.”
Her colleague Dr Clair Barnes, an expert in extreme weather and climate change at Imperial, framed the estimates as both a warning and a hope. “If by putting out these estimates we highlight to people how dangerous it is and they change their behaviour next time there’s a heatwave and our estimates turn out to be high, I will be thrilled,” she said. “These are big numbers and we don’t want to see this many people dying.”
## Lessons From 2025
There is reason to believe that public awareness and institutional preparation can make a measurable difference. Experts had expected 2025 to be a very bad year for heat-related deaths, with a predicted toll of 3,039. In the event, the actual number was roughly half that figure.
The UK Health Security Agency attributed the lower-than-expected death toll to heat health alerts and action taken across the NHS and care systems. This suggests that early warning, coordinated planning, and behavioural change can save lives — even when the weather itself is extreme.
## What Comes Next
Looking ahead, the researchers warn that the trajectory is concerning. On current paths, heat-related deaths in parts of northern Europe could begin to rival cold-related ones within a couple of decades. They are careful to note, however, that this outcome is not inevitable. It depends heavily on how quickly the world cuts greenhouse gas emissions and how effectively countries adapt their infrastructure and public health systems to a warming climate.
The broader scientific consensus is clear: heatwaves are expected to become more frequent, more intense, and longer-lasting the more greenhouse gases are emitted. The May and June heatwaves in England and Wales are consistent with that pattern, and they offer a vivid illustration of what it means in practice.
## The Built Environment Problem
One factor that receives less attention than it deserves is housing. Many UK homes were designed for a cooler climate. They are poorly suited to coping with prolonged, high temperatures, retaining heat in the summer and offering little in the way of active or passive cooling. This leaves occupants — particularly older people and those in urban areas — vulnerable during extended heat events.
The problem is structural, and it will not be solved by individual behaviour alone. Retrofitting homes, improving urban green space, and rethinking building standards are all part of the adaptation conversation. But for now, during the heatwaves themselves, the burden falls on individuals to stay hydrated, seek shade, check on vulnerable neighbours, and take the warnings seriously.
The estimate of more than 2,700 deaths is, in the end, a number. But behind each unit in that number is a person, a family, and a story. The researchers’ hope is that by making the scale of the risk visible, fewer of those stories will need to be told next time.