- More than 1,100 NHS operations were cancelled because of extreme heat.
- At least 10 emergency procedures were among the cancelled operations.
- Heat caused ventilation and air-conditioning systems in theatres to fail.
- Orthopaedic, eye and other planned surgeries were heavily affected.
- Experts warn NHS hospitals remain poorly prepared for rising temperatures.
More than 1,100 operations at NHS hospitals in England and Wales were cancelled because of extreme heat during the record-breaking heatwaves of May and June 2026.
The figure comes from an investigation based on Freedom of Information requests sent to 140 NHS trusts and health boards. Of those contacted, 59 provided details of heat-related cancellations, recording 1,110 affected operations over 17 days during the two heatwave periods.
The true number is likely to be considerably higher because many NHS trusts do not routinely record whether cancelled procedures were caused by extreme heat.
The cancellations included routine operations such as knee and hip replacements, but the disruption went beyond elective care. At least eight heart operations, seven skin-cancer procedures and 10 emergency surgeries were cancelled because of heat. A further 18 procedures were abandoned after they had already begun.
Surrey and Sussex Healthcare NHS Trust recorded the highest number of cancellations, with 140 operations affected at Crawley Hospital. Temperatures in the area approached 36C during June.
How does extreme heat affect operating theatres?
The problem is not simply that hospitals become uncomfortable when temperatures rise.
Operating theatres are highly controlled environments. Their ventilation systems regulate temperature and humidity while also helping remove airborne contaminants, fumes and anaesthetic gases.
When these systems cannot maintain safe conditions, surgery may have to be stopped or cancelled.
Dr Ed Robinson, an NHS anaesthetist, explains why:
“An operating theatre is a very tightly engineered clinical environment. There are quite complicated ventilation systems, which dilute airborne contaminants, remove fumes from different [medications] and anaesthetic gases.
“We have generalised airflow systems that make the air in theatre flow outwards to adjacent areas, so pathogens and fumes get carried away from the patient into non-clinical areas. When it gets to a certain heat, those systems can fail.”
Carbon Brief's investigation found 48 cases in which hospitals specifically identified air-conditioning or ventilation systems as broken or unable to maintain appropriate temperatures.
Humidity creates another concern. Excess moisture can condense on surgical equipment and potentially increase infection risks.
High temperatures can also affect staff. Surgeons and theatre teams often work in heavy protective clothing, sometimes for lengthy procedures. Excessive heat can cause fatigue, reduce concentration and make safe surgery more difficult.
Patients face more than a delayed operation
Most of the cancelled procedures were elective, meaning they had been scheduled in advance rather than being immediately life-saving.
That does not mean the consequences are minor.
Orthopaedic operations accounted for 167 of the 596 cancellations for which detailed procedure information was available. Eye, gynaecological and urological operations were also among the procedures most frequently affected.
Dr Dmitri Nepogodiev, a public health researcher specialising in surgery at the University of Birmingham, says hospitals will prioritise the most urgent cases. But cancelling any procedure can still have a significant effect on patients.
“Behind all of these statistics…are real people who have probably already been waiting a long time.”
Richard Egan, an endocrine surgeon and national clinical director within NHS Wales, also warned about the impact on already lengthy waiting lists:
“That’s a significant impact on waiting lists…For every week that patients are waiting on a waiting list, their condition could get worse and deteriorate.”
For patients, therefore, a heat-related cancellation can mean prolonged pain, reduced mobility, worsening illness or further anxiety about when treatment will finally take place.
Why is the NHS struggling to cope with heat?
The cancellations highlight a wider problem: much of the NHS estate is ageing and was not designed for increasingly frequent periods of extreme heat.
Research following the 2022 heatwave found that temperatures could not be adequately controlled in two-fifths of NHS operating theatres. The study concluded that UK surgical services were “poorly prepared for heatwaves”.
The challenge has become more urgent as climate change increases the likelihood and intensity of extreme heat.
Tim Lane, a urological surgeon and president of the Royal College of Surgeons of England, says:
“Extreme heat can increase risks and make it harder to deliver care under the conditions clinicians would consider ideal.”
Heat can also affect medical equipment and medicines. Robinson notes that some products are only validated for use within specific temperature ranges. This includes specialised cement used in hip and knee replacements, which can set too quickly at higher temperatures.
What can be done?
There is no single solution.
Hospitals need better cooling and ventilation, more resilient buildings and clearer plans for operating during extreme weather. Staff may also need guidance on which procedures can safely continue at higher temperatures and which should be postponed.
Dr Nepogodiev describes the challenge as complex:
“There isn’t a single magic solution because it’s a kind of complex, multifactorial challenge – so it also underlines the importance of broader preparedness.”
The UK government has already announced £32m from a £1.5bn programme for projects designed to strengthen hospitals' resilience to extreme heat, including improvements to cooling and ventilation systems.
But experts argue that investment needs to go further.
RCS England president Lane says:
“NHS staff work incredibly hard to adapt, often reorganising services and finding practical solutions to keep care running, but resilience alone cannot compensate indefinitely for outdated infrastructure or sustainability.”
The latest cancellations demonstrate why preparing for heat can no longer be treated as an occasional summer issue. As extreme temperatures become a growing threat, hospitals will need infrastructure capable of protecting patients and staff while keeping essential surgery running.
For the NHS, the lesson from the 2026 heatwaves is clear: preparing for extreme heat is increasingly a patient-safety requirement, not simply a facilities-management problem.
