A research team comprised of experts from Imperial College London, the Met Office, and the London School of Hygiene and Tropical Medicine has estimated that thousands of people may have died due to record-breaking heatwaves that struck the UK in May and June.
The study, which utilizes death records from previous years to model the impact of the 2026 events, suggests that the majority of these fatalities occurred during the June heatwave.
That month was recorded as the warmest June in England, with temperatures reaching 37.7C (99.9F) in Lingwood, Norfolk, significantly exceeding the previous record of 35.6C set in 1957.
During this period, authorities issued a rare red heat alert for parts of England and Wales, warning that even healthy individuals faced a significant risk to life. May also saw record-breaking temperatures, hitting a new UK high of 35.1C at Kew Gardens on May 26, which surpassed the previous record of 32.8C established in 1922 and equaled in 1944.
Experts attribute both heatwaves to a "heat dome," a stalled area of high pressure that trapped hot air over the region.
Researchers emphasize that human-induced climate change, which has warmed the planet by approximately 1.4C since pre-industrial times, exacerbated these conditions. Scientists believe this added between 3 and 4C to the maximum temperatures recorded during the two months.
The impact was further intensified by hot tropical nights, which provided little relief, and the fact that many UK homes are not constructed to handle such prolonged high temperatures.
Extreme heat places significant physical strain on the body, forcing the heart to pump harder and faster as it attempts to cool the individual down. This risk is particularly high for babies, the elderly, and those with existing health conditions. The situation is often described as a "silent killer" because early symptoms can be easily overlooked, and the condition can lead to fatal emergencies such as heart attacks and strokes.
Furthermore, high humidity levels, which were present in June, made it more difficult for the body to cool itself through sweating.
Dr. Clair Barnes, an expert in extreme weather and climate change at Imperial College London, stated, "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.
These are big numbers and we don't want to see this many people dying." While the study makes assumptions about the severity of the impact, the UK Health Security Agency (UKHSA) noted that heat health alerts and proactive measures across the NHS and care systems likely reduced the overall impact.
Experts warn that as greenhouse gas emissions continue, heatwaves are expected to become more frequent, intense, and longer-lasting.
