Heatwaves in Europe have arrived unexpectedly early this year with two major spikes in temperatures already affecting millions of people and a third gripping parts of the continent.

From late June to mid-July, temperatures soared as high as 46 degrees Celsius (114 degrees Fahrenheit) with some locations in Western Europe experiencing record-breaking heat.

Wildfires in Greece have triggered evacuations while in France, emergency measures have closed schools and even the Eiffel Tower. In Italy, bans on outdoor labour have affected many workers.

Spain’s environment ministry said high temperatures have caused 1,180 deaths in the past two months, a sharp increase from the same period last year.

According to a study, about 2,300 heat-related deaths were recorded in 12 European cities from June 23 to July 2. About 1,500 of those deaths were linked to climate change, according to the researchers at Imperial College London and the London School of Hygiene and Tropical Medicine.

“Climate change has made it significantly hotter than it would have been, which in turn makes it a lot more dangerous,” Dr Ben Clarke, a researcher at Imperial College London, said.

Where have heatwaves occurred?

The first heatwave Europe experienced peaked between June 17 and 22 and affected Western and Southern Europe.

During the second heatwave, peaking between June 30 and July 2, temperatures exceeded 40C (104F) in several countries with some cities in Spain and Portugal reaching 46C (118F).

What is causing the heatwaves?

The persistent heat is being driven by a high-pressure system over Western Europe known as a heat dome.

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It acts like a lid that traps hot air under it. The pressure from the weather system pushes air down into a hot, dome-shaped mass and prevents milder weather systems from moving through.

As a result, it creates prolonged periods of excessively high temperatures.

The heat in turn prevents clouds from building up, reducing the chances of rain.

This June was the warmest on record for Western Europe

Due to the weather phenomenon, Western Europe saw its warmest June on record with an average temperature of 20.49C (68.88F), surpassing the previous record for the month from 2003 by 0.06C (0.11F), according to the Copernicus Climate Change Service.

On June 30, temperatures averaged 24.9C (76.8F) over Western Europe, setting a new daily temperature record for June. The same average temperature was recorded on July 1.

That was one of the highest daily temperatures ever observed in Europe during this time of year. It was exceeded only during the heatwaves of 2003, 2018, 2019, 2022 and 2023.

Europe is the fastest warming continent and has warmed by 0.53C (0.95F) per decade since the mid-1990s, according to the ERA5 dataset from the Copernicus Climate Change Service.

Several factors are causing this effect in Europe, including shifts in atmospheric circulation, leading to more frequent and intense heatwaves. Additionally, reduced air pollution means that more solar radiation is reaching the Earth’s surface and reducing cloud cover. Certain areas of Europe also extend into the Arctic, which is the fastest warming region on the planet.

Countries such as the United Kingdom, France, Spain and Portugal saw the hottest temperatures recorded since 1979 from the start of the first heatwave to the end of the second heatwave – June 17 to July 2.

Heat-related deaths in Europe

Heatwaves have been deadly for Europe.

A report by Imperial’s Grantham Institute published last week studied 12 European cities to measure changes in the intensity of heatwaves.

From June 23 to July 2 it estimated there were 2,300 heat-related deaths, including 1,500 linked to climate change, which made the heatwaves more severe.

Climate change was behind:

• 317 of the estimated excess heat deaths in Milan
• 286 in Barcelona
• 235 in Paris
• 171 in London
• 164 in Rome
• 108 in Madrid
• 96 in Athens
• 47 in Budapest
• 31 in Zagreb
• 21 in Frankfurt
• 21 in Lisbon
• six in Sassari, Italy

The study found that the heatwaves were more deadly due to the early arrival of higher temperatures, which usually occur in late July and in August.

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People in Europe are not acclimatised to such high temperatures, especially the older population. More than 80 percent of the estimated excess deaths are expected in people older than 65.

The world is getting hotter

Last month was the third warmest June globally since 1850, according to average temperatures. June’s average surface air temperature was 16.46C (61.62F) to 0.47C (0.84F) and higher than the 1991-2020 average for June, according to the Copernicus Climate Change Service.

Global temperatures remain unusually high, closely tracking 2024 – the hottest year on record, having averaged a surface air temperature of 15.1C (59.18F), which was more than 1.5C (2.7F) higher than pre-industrial levels, a threshold seen as crucial to avoid dangerous global warming.

An article published last month in the Earth System Science Data journal also noted that human-induced warming has been increasing at a rate of 0.27C per decade from 2015 to 2024, which is the highest rate observed in the instrumental record.