A vast heat dome parked over Western Europe pushed temperatures beyond 45°C this week and triggered red, top-tier heat warnings across France, Italy, Spain and — unusually — the United Kingdom, as forecasters warned that several national June records were likely to fall on June 24 and 25. By June 24 roughly two-thirds of mainland France was under a red alert, Italy had placed 16 major cities including Rome, Milan, Florence and Turin under its highest health warning, and Britain’s Met Office had issued a rare red extreme-heat warning for parts of England.
The early-summer timing is what alarms meteorologists most. Heat of this severity typically arrives in late July or August; this dome built in the final week of June, with temperatures running 10 to 15°C above seasonal norms across central Europe. Spain recorded the continent’s peak so far — 45.1°C at Andújar in Andalusia on June 22 — while France hit 44.3°C at Pissos in the Landes and 41.1°C in Bordeaux, with the southwest bracing for a multi-day plateau near 45°C.
In Britain, the Met Office said the country’s highest June temperature on record — 35.6°C, set in Southampton in 1976 — was "very likely" to be broken, with forecasts approaching 38°C in the southeast. The London Underground, never designed for such conditions, recorded 34.3°C inside trains and stations, and operators urged passengers to carry water.
The human cost is already heavy. Spain has reported roughly 209 heat-linked deaths so far this season, with a sharp rise since the latest spike began on June 21. France has logged dozens of fatalities, including at least 40 drownings — many of them young people seeking relief in unsupervised rivers and lakes — prompting Prime Minister Sébastien Lecornu to warn of "a tragic scourge of drownings." Britain has recorded at least 15 water-related deaths.
Authorities have responded with the now-familiar machinery of a European heat emergency. France closed around 845 junior and middle schools and adjusted schedules at some 1,800 more, while about 68,000 French households lost power as demand and heat-stressed equipment strained the grid. In Turin, overheating underground cables triggered repeated blackouts, a reminder that the damage extends well beyond human health to the physical systems cities depend on.
The pattern of impacts illustrates why heat is sometimes called Europe’s deadliest and most underestimated weather hazard. Unlike a storm or flood, its toll accumulates quietly — in emergency-room admissions, in excess deaths among the elderly and chronically ill, and in drownings that rarely make a single dramatic headline. The deadliest event in modern European memory, the 2003 heatwave, killed an estimated 70,000 people across the continent, and most of those deaths were never witnessed as a disaster in the conventional sense.
Scientists have repeatedly found that climate change makes heatwaves of this magnitude both more frequent and more intense. Each fraction of a degree of warming widens the envelope of possible extremes, so events that were once rare now recur every few years, and records that stood for decades fall in clusters. The early onset of this week’s heat — and the breadth of countries simultaneously under red alert — fits that trajectory closely.
Forecasters expect the dome to begin breaking down later in the week as cooler Atlantic air pushes in from the west, bringing relief first to France and Britain and the risk of violent thunderstorms as the hot and cold air masses collide. Until then, governments have urged residents to check on elderly neighbours, avoid midday exertion and stay out of unsupervised water — the simple measures that, in the absence of widespread air conditioning, still do most to keep the death toll down.