UK Sets All-Time June Temperature Record at 35.7C as Europe's Heat Dome Expands East, Killing 40 in France

Since the heatwave established its grip on Western Europe earlier this week, the story has moved steadily eastward and gotten measurably deadlier. Wednesday, June 24 is delivering new records on top of the ones already logged.

The UK Joins the Record Books

Surrey recorded 35.7C on Wednesday, according to the Guardian, eclipsing the previous all-time June record of 35.6C set in Southampton during the 1976 heatwave. Scotland also recorded its hottest day of the year on Wednesday, per the same source.

The BBC explains why this heatwave feels worse than May's, even where raw temperatures are lower. During the May event, the heat dome sat directly over the UK, producing hot but dry air. This time the dome originated over the humid sub-tropics and is centered on France. The result for southern England is a south-easterly flow pulling in moist air. Dr. Akshay Deoras, senior research scientist at the University of Reading, told BBC Weather: "This is not just a heatwave, it is a heat-dome driven furnace that will grip most of the southern UK and push temperatures into truly exceptional territory." Where thermometers read 35C, it can feel like 41C once humidity is factored in.

Eurostar canceled four trains between London and Paris on Wednesday and Thursday due to the heat, according to the Saudi Gazette.

France: Records, Outages, and Deaths

Tuesday was France's hottest day since national records began in 1947. The country's national temperature indicator, an average of daytime and nighttime readings across 30 stations, hit 29.8C, per AFP via Dawn.com. Pissos, in the southwest Landes region, reached 44.3C. Bordeaux has broken its own all-time record three days in a row: 41.8C Monday, 42.1C Tuesday, with Wednesday readings still coming in as of this writing.

Fifty-eight of France's 96 mainland departments are now under a red heat alert, with 31 more on orange, according to Météo France. AFP calculates that roughly 44 million people fall under the highest alert tier alone, and more than 90 percent of the French population is exposed to extreme heat.

At least 40 people have drowned in heatwave-related incidents in France since last Thursday, according to the prime minister. Most victims were young and swimming in unsupervised water, per the New York Times.

The 68,000-home power outage in Brittany's Finistère department, reported in our earlier coverage, remains only partially restored as of Wednesday. Dawn.com reports the peak outage reached 106,000 clients before crews began repairs overnight.

Air Conditioning: France's Uncomfortable Debate

The BBC reports that France, where only 25% of households own an air conditioner, is now being forced into a genuine policy argument. Carrefour CEO Alexandre Bompard told reporters the retail chain sold 30,000 air-conditioning units in a single day on Monday, "a thousand times more than on a normal day." Amazon France sales of cooling units nearly doubled last week compared to the same period in 2025, per Dawn.com.

The political divide is real. Marine Le Pen is calling for a mass subsidized rollout. The Ecologists' leader Marie Tondelier broke with her party's traditional position, saying "there are places where we just can't do without it now," specifically naming schools and hospitals.

The environmental concern underlying the resistance to air conditioning is not trivial. Cooling units require electricity, use refrigerant gases that leak greenhouse compounds, and expel hot air onto streets. Some studies, cited by the BBC, suggest urban heat expulsion can raise city temperatures by two to three degrees. That is a legitimate feedback loop.

French hospitals and schools currently lack cooling equipment, thousands of schools have already shut this week, and medical staff are reporting intolerable working conditions, according to the BBC. At some point the concrete problem of keeping patients and children alive in 40C heat collides directly with the abstract debate about long-term climate feedback. SNCF CEO Jean-Pierre Farandou told French radio: "We're in the process of finding out we've become a hot country" and warned that society needs to adapt.

The Spread Eastward

The Guardian estimates 94 million Europeans will experience temperatures above 35C on Wednesday alone. The Netherlands is under an orange alert today. Belgium and the Netherlands are expected to peak Friday. Germany could see 40C over the weekend. Severe heat warnings have been issued for Poland, Croatia, and Hungary for later in the week, according to BBC News and the Saudi Gazette.

Some relief is forecast for France starting Friday, but it arrives with thunderstorms, flash flooding risk, and large hail, per Météo France.

The Unanswered Question

Europe built early warning systems and cooling shelters after the 2003 heatwave killed an estimated 70,000 people. Paris created a registry of elderly residents who receive check-in calls during extreme heat events. The New York Times quoted one public health expert who said, "We have adapted, but it is far from enough for what is coming." Whether those systems hold under a heatwave that is simultaneously broader, more humid, and longer-lasting than 2003 is the question that will be answered in the next 72 hours, as the heat dome pushes through populations in Eastern Europe with no comparable warning infrastructure.