Sweltering temperatures are shattering records across Europe, as the continent battles a deadly heatwave.
On Tuesday and Wednesday, France endured its hottest days in history, with western regions reaching highs of between 39°C and 43°C. Wednesday was the United Kingdom's warmest June day on record, with the mercury climbing to 36.1°C. And according to early data , Spain, Germany, Austria, the Netherlands and Switzerland have all broken June temperature records at several sites. And the event is not over yet.
Tragically, lives have already been lost, including dozens of people who have drowned in France in the past week, while trying to cool down in the punishing heat.
But this historic heatwave is not happening in isolation. It comes days after the global sea surface temperature again reached record levels. Meanwhile, Australia's weather bureau has declared El Niño active , making a hotter, drier year in Australia, Asia and the South Pacific much more likely. And since April, India and Pakistan have been battling a sustained and ultimately deadly heatwave.
So what's driving this latest heatwave? And why is it so severe?
An unusual heatwave
A heatwave occurs when the average temperature is unusually hot for three or more days in a row. That's compared to past weather data taken from the same location.
But scientists are losing sleep over the current European heatwave, for two main reasons.
1. Timing
In Europe, the hottest time of year comes in mid- to late July , about a month after the summer solstice. However, recent research suggests days of intense heat stress are now starting to arrive in June. Since 1950, only one other major heatwave has arrived earlier than the current heatwave, which is unfolding weeks before the peak of the European summer.
Current evidence shows climate change is making heatwaves more frequent and intense. One study examined the heatwave that hit southeast England in June 2025. It found that without the effect of human-made greenhouse gas emissions, such a heatwave would only happen once every 50 years. But when the researchers accounted for the temperature increase of 1.3°C caused by human-induced climate change, this became at least once every five years.
2. Severity
In a world without climate change, this extreme heatwave would rarely if ever happen so early in the year. And it also would not be toppling temperature records, and by such staggering amounts.
Tuesday and Wednesday were France's hottest days since records began in 1947, with an average temperature of 29.9°C across the country. On Tuesday, 147 French towns hit all-time highs for June, with 41 local weather stations recording figures above 43°C .
France also slept through its warmest night ever from Tuesday into Wednesday, with a national average temperature of 21.6°C. The overnight heat was enough to make some rivers so warm they could not be safely used to cool nuclear power plants.
In the same week, Spain also set multiple daytime and nighttime records, with one location enduring three consecutive nights of 30°C or above . Parts of Spain have seen temperatures surpass 45°C .
In western Europe, the heatwave is expected to peak in the middle of this week before shifting east, with forecasts suggesting Poland and Germany will bear the brunt over the weekend.
What caused it?
At the local scale, heatwaves occur when a high-pressure system settles over a region. These systems act as "lids" that trap heat and push it closer to the surface. They also disperse clouds to allow more sunlight to stream in.
On a broader scale, climate change from the burning of oil, coal and gas is reshaping how and when heatwaves form. This is because the additional heat trapped in the atmosphere also changes large-scale weather patterns , which typically move east to west, allowing more slow-moving high-pressure systems to form. This in turn increases the risk of heatwaves.
Research shows in the five decades between 1950 and 1999, Europe endured five intense heatwaves. Between 2000 and 2021, there were 18 such heatwaves. Add to that the extreme heatwaves of 2022, 2023 and 2025, and this figure rises to more than 20 severe heatwaves in just 25 years. So the evidence is clear - European heatwaves are happening far more often.
How are people coping?
This heatwave has already tragically claimed dozens of lives in France, where people have drowned .
According to the European Climate Risk Assessment, heatwaves already pose a critical health risk to people across southern Europe. And in coming years, communities in southern and western-central Europe will be most at risk of heat-related illness and death.
What makes this heatwave so severe is the combination of extreme temperatures and high humidity , which is completely unlike the typical dry summers experienced in southern Australia.
Children and the elderly are most at risk of heat-related illness. Their bodies are less able to evaporate sweat and regulate their internal temperature . For these populations, extreme heat coupled with humidity can be life-threatening .
What about the next southern hemisphere summer?
Historically, heatwaves in Europe aren't related to heatwaves in the following southern hemisphere summer.
However, climate change is increasing the risk of extreme heat in any given year. Combine this with the effects of El Niño, and global average temperatures will be at near-record levels for both 2026 and 2027.
In our changing climate, the risk of extreme heat - Australia's deadliest natural hazard - is now a global reality.
Andrew B. Watkins is a Climate Councillor with the Climate Council.
