Record-breaking heatwaves in May and June are estimated to have caused 2,877 excess deaths in England, according to provisional figures released on Wednesday by the UK Health Security Agency (UKHSA).
The toll is almost double the 1,504 excess deaths recorded during the entire summer of 2025, with the agency describing the latest figures as evidence of a “substantial public health impact.”
“These figures highlight the significant danger that very hot weather can pose to people’s health,” said Ross Thompson, Principal Environmental Public Health Scientist at the UKHSA.
Health Secretary Yvette Cooper said the country has traditionally associated higher illness and mortality with winter, but warned that extreme summer temperatures are becoming an increasingly serious public health challenge.
“We are accustomed to higher rates of illness in winter, but now we are seeing the summer heat have an increasingly serious impact on the health of thousands of people,” she said.
The UKHSA noted that the latest estimate does not include July, which has also experienced prolonged periods of extreme heat, meaning the final death toll for the summer is expected to rise significantly.
“Based on the interim data, it is likely that 2026 could see the highest number of heat-associated deaths on record,” the agency said.
The estimate of excess deaths is calculated by comparing average mortality on days when temperatures exceed 20 degrees Celsius with average deaths recorded during cooler periods.
According to the agency, 753 excess deaths were recorded in May, while June accounted for 2,124 deaths, when parts of the country were placed under a rare red heat warning.
The UKHSA urged communities, healthcare providers and public services to prepare for extreme heat from the beginning of summer rather than waiting until temperatures peak, warning that heatwaves are becoming an increasingly frequent and deadly consequence of climate change.