Nearly 2,000 schools were shut in France, monuments closed to tourists, and cities across Europe put on high alert as a record-breaking early summer heatwave spread across the continent Tuesday.
Withering conditions that have baked southern Europe for days crept northward where such extremes are much rarer, with Paris on "red alert" and warnings issued in Belgium, Switzerland and Germany.
Tens of thousands of people have died in Europe during past heatwaves, prompting authorities to issue warnings for old and young, the sick, and others vulnerable to what experts call a "silent killer".
On Tuesday, police in Spain said a two-year-old died in the country's northeast after being left in a car in the sun for several hours.
The EU's Copernicus Climate Change Service (C3S) warned that millions of Europeans were exposed to high heat stress, and that temperatures would remain "well above average" across most of the continent in coming days.
"This event is unusual because it's extreme, because it's very early on in the summer period, and climate change has almost certainly made it worse than it otherwise would have been," climate scientist and C3S deputy director Samantha Burgess told AFP.
Records have already tumbled, with the Netherlands experiencing its hottest opening day of July, France and Portugal their highest-ever single-day temperatures in June, and Spain and England their warmest June months.
On Sunday, in a case of two extremes, the Mediterranean Sea hit a new June temperature record while Mont Blanc, the highest peak in Europe, went above freezing, a rarity for this time of year.