Autumn in name only
Summer was supposed to be over. Instead, a vast dome of high pressure parked itself over western and central Europe in late September, trapping warm air beneath it and sending thermometers soaring to levels more typical of July. Almost 32°C was recorded in Germany, over 30°C in Switzerland, and 33°C in France — and forecasters warned it was just the beginning of a heat wave set to rewrite European climatic history, with thousands of records expected to fall by margins of five or six degrees.
The numbers from mid-September tell the story of a continent running far hotter than it should. Temperatures across large parts of Europe were 4 to 8 degrees Celsius above average for the time of year. Eastern Germany and eastern Poland pushed up to 30°C; southwestern Germany reached 32°C. Central France hit 33°C, with much of the country near or above 30°C. Northwestern Sardinia touched 33°C, and southwestern Spain climbed all the way to 36°C. The Mediterranean Sea itself remains much warmer than average — a reservoir of heat that feeds back into the atmosphere and supercharges autumn storms.
According to calculations by the AFP news agency, based on forecasts from the German weather service and population projections from the EU's Joint Research Centre, more than 380 million people across Europe — nearly two-thirds of the continent's population — faced temperatures exceeding 30°C on a single Thursday in late September. In Italy, 48 million people endured temperatures above 30°C; in Germany, the figure was 70 million. Belgium, Luxembourg, the Netherlands, Poland, Hungary, the Czech Republic and Croatia were all caught under the same heat dome.
The science: a continent warming fastest
The immediate cause of the extreme temperatures is a 'heat dome' — an area of high pressure that becomes stuck over a region, trapping warm air underneath and preventing cooler air from moving in. While it is difficult to link any single extreme weather event directly to climate change, scientists say climate change makes heatwaves more frequent, more intense and longer-lasting.
Over the past 30 years, Europe has been warming at a rate of 0.56°C per decade, according to the Copernicus Climate Change Service — making it the fastest-warming continent on Earth. The UN warned this week that global average temperatures were likely to continue at or near record levels this year and for the next four years, with the strengthening El Niño adding another layer of heat to an already overheated system.
France's summer underlined the trend. The country's minister for ecological transition confirmed it was the hottest summer since measurements began in 1900, and the heat rolled on into September: France set a new national September record of 40.3°C, while Marseille — with records stretching back to 1868 — set a new September record by an extraordinary 6.5°F margin, reaching 37.4°C. Spain, Portugal and other parts of western Europe saw similar extremes.
The human cost
Heat is the deadliest form of extreme weather, and this summer's toll across Europe has been severe. Excess mortality figures compiled across the continent run into the tens of thousands, with Germany, France, Spain, the UK and Italy all reporting thousands of heat-related deaths. The pattern of excess mortality mirrors what happened across Europe in the summer of 2003, when an estimated 70,000 people died in a heatwave that at the time was considered exceptional.
Climate scientists now say that what was exceptional in 2003 is becoming routine — and that the summers of the 2020s represent a new baseline rather than an outlier. The elderly, outdoor workers, and residents of poorly insulated urban housing face the greatest risk, particularly during prolonged episodes when warm nights — forecasters warned of lows around 25°C in Toulouse, Perpignan, Montpellier and Marseille — prevent the body from recovering.
The economic bill: €113 billion
This week, a joint study by Allianz and Allianz Trade put a price on the summer's heat. Across the countries studied, heat-related economic losses are estimated at €113 billion, with Germany the second hardest-hit in Europe at €25 billion — behind Italy at €28 billion and ahead of France at €20 billion.
The losses flow through multiple channels: reduced labor productivity as workers slow or stop in dangerous heat, damaged crops and livestock, strained energy grids, disrupted transport, and surging healthcare costs. The study's authors stress that the figure captures only part of the damage, since many heat effects — from long-term health consequences to ecosystem degradation — resist easy quantification.
Looking ahead, the study also modeled the economic impact of a strong El Niño — now confirmed as a record-strength super event — based on the 2023–24 episode. Across 144 global economies, it could result in around €392 billion ($451 billion) in lost economic output next year, with China, the US and India accounting for almost 60 per cent of gross losses. The 27 EU member states would face losses of around €21 billion ($24 billion), equivalent to about 0.9 per cent of GDP, with a 0.31 percentage-point effect on overall inflation and a 0.5 percentage-point impact on food prices.
'The heatwave summer of 2026 shows how quickly things can change,' said Hazem Krichene, senior climate economist at Allianz. 'It is therefore crucial to invest in adaptation and prevention in a timely manner. Ongoing prevention, forward-looking financing, and clear lines of responsibility make more economic sense than ever-increasing expenditures for repairing damage that has already occurred.'
Britain's worst harvest on record
One of the starkest illustrations of the summer's damage comes from the fields. The UK is set to face its worst harvest on record, according to analysis of the latest crop numbers from the Agriculture and Horticulture Development Board (AHDB). Spring barley is down 17 per cent compared with the UK five-year average, oats are down 14 per cent, and winter wheat is down 11 per cent.
The AHDB described the harvest as 'rapid and straightforward but with very disappointing yields' — the crops came in quickly because the drought-stressed plants matured early, but there was simply less grain to gather. For British farmers, it caps a brutal year; for consumers, it adds pressure to food prices already strained by extreme weather worldwide.
Adaptation is no longer optional
The late-September heat dome is a reminder that Europe's climate challenge is no longer about preparing for a distant future. Cooling centers, heat-health warning systems, revised building codes, urban greening, and crop varieties bred for drought are becoming basic infrastructure — as essential as flood defenses were a generation ago.
The Allianz researchers' prescription is blunt: adaptation measures such as early-warning systems, risk mapping, forward financing and clear lines of responsibility need to be ramped up now. Prevention, they argue, is not just more humane than repair — it is cheaper. With another hot week forecast and a record-strength El Niño still peaking, Europe will not have to wait long to test that proposition.
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