The UK Met Office issued a rare red extreme heat warning on June 22 for parts of southern England and Wales, covering June 24 and 25, with temperatures expected to exceed 37C and possibly reach 40C in some areas [1, 2, 3, 4, 5, 6]. On June 24, southern England recorded the hottest June temperature on record, with provisional measurements between 35.7C and 36.1C, surpassing the previous June record of 35.6C set in 1976 [4, 5, 6].
The heatwave follows a series of unusually high temperatures in the UK, which had already broken May heat records. The Met Office expanded warnings in the days leading up to June 24, predicting highs between 38C and 40C in some locations [7, 8, 9, 1, 2]. Met Office deputy chief forecaster Gregory Wolverson described the week as showing “a contrast we often see in summer, with more unsettled conditions passing to the north-west of the UK while heat builds in the south and east” [7].
The extreme heat combined with humidity has caused serious public health risks, power grid strain, and infrastructure disruption. High humidity is producing tropical nights where temperatures stay above 20C, increasing discomfort and health dangers [9, 3, 4]. Met Office chief forecaster Matthew Lehnert said, “High humidity is an additional factor for this heatwave, which will mean the heat will feel much more potent for many” [4].
The UK’s grid operator, National Electricity System Operator (Neso), issued a rare summer electricity margin warning on June 23. It requested an additional 1.9 gigawatts of power capacity from generators to meet peak demand on the evening of June 24 [10, 11].
Schools across southern England and Wales closed either fully or partially around June 23 to 25, totaling at least 300 institutions [2, 3, 5, 6]. Rail companies reduced services and urged passengers to travel only if necessary during the heatwave due to heat-related damage risks to infrastructure [2, 3, 5, 6].
Authorities issued successive amber and yellow heat and health warnings starting June 18, escalating to extreme amber and red warnings by June 23 for England and Wales [7, 8, 9, 1]. Public safety notices also warned of water safety risks, including cold-water shock and drowning, as more people sought relief in lakes and beaches. RNLI water safety manager Ross MacLeod advised, “Cold water shock is a real danger...It’s best to enter the water slowly to gradually acclimatise. Anyone who finds themselves in danger in the water should fight the panic instinct and ‘float to live’” [7, 8, 9].
Climate experts and officials have cited human-induced climate change as a key factor making such extreme heat events more likely and intense. Met Office chief scientist Stephen Belcher said, “Human induced climate change has made events like this more likely and more intense” [2]. Tedros Adhanom Ghebreyesus, WHO Director General, warned Europe’s heatwave is putting lives at risk, with temperatures rising at roughly twice the global average rate [4]. UCL professor emeritus Bill McGuire predicted, “As 40+ temperatures become ever more common, expect many thousands sleeping in the streets as poorly insulated homes become uninhabitable heat traps, widespread power cuts...and A&E departments overwhelmed” [1].
The LSE Grantham Institute cancelled a planned climate event due to the red heat warning, illustrating the wider societal repercussions [12]. The UK continues to experience extreme heat impacts as the red warning remains in effect through June 25 [1].
