Deaths in Britain linked to soaring temperatures in May and June this year have nearly doubled the entire figure for 2025, with 2,877 fatalities recorded, according to new data. The UK Health Security Agency (UKHSA) released the report following two significant heat events that saw record-breaking temperatures impact public health. In 2025, a total of 1,504 heat-related deaths were recorded. The current figures for May and June stand at 2,877, with numbers anticipated to rise. An estimated 753 deaths were associated with a heatwave between May 24 and May 27, which occurred early in the season. A further 2,124 deaths have been linked to sustained high temperatures throughout June.
The UKHSA notes that these are early estimates, but they indicate that heat deaths are rapidly approaching the annual record set in 2022. Britain experienced its hottest ever June day last month, with temperatures reaching 38C.
Heat health alerts, both amber and yellow, are currently in effect as parts of the UK face the fourth heatwave of the year. A heat episode is defined as days when the average temperature in England is at least 20C. The May heatwave saw maximum temperatures of 35.1C in Kew Gardens, London, with average temperatures around 23.2C. Daily deaths peaked on May 26, the hottest day of that period. The June heatwave, from June 21 to June 28, resulted in approximately 266 heat-related deaths per day.
'The estimated 2,877 heat-associated deaths observed across the May and June episodes represent a substantial public health impact,' the UKHSA stated. 'The timing of these events are particularly noteworthy. Early-season heat can pose particular risks as unusually hot weather may occur before people, communities and services have fully prepared and are ready to respond to hot weather conditions.'
High temperatures place significant strain on the body's organs. As body temperature increases, more blood is directed to the skin to aid cooling, which increases the heart's workload. Dehydration can also thicken blood, elevating the risk of heart attacks and strokes.