Towards the end of June, heat gripped much of Europe, baking France, Spain, Germany, Czech Republic, Denmark, Poland and the UK.
In many places, heat was in competition with, well, itself. According to France’s meteorological administration, Météo-France, June 24 was the hottest day on the record. It broke the record set on June 23.
“Wednesday June 24 and Thursday June 25 were the hottest days ever recorded in France, reaching 30C for the first time on average over 24 hours and ahead of 29.9 C on Tuesday June 23,” said France’s Met department in a statement.
The latest escalation of heat beat previous hottest records set on July 25, 2019, and August 5, 2003.
Paris, the capital of France, has recorded more days above 40C this week than during the 147-year period spanning from 1872 to 2019, according to Nahel Belgherze, a researcher at the Finnish Meteorological Institute.
“Historic is an understatement,” he wrote in his post on X.
Spain recorded 45C on June 22 in Andujar, while Santon Downham in the UK broiled at 37.2C on June 26.
While high temperatures are not unusual in summer, the extent and persistence of heat during June 2026 is particularly notable. Records dating back several decades, in some cases over a century, were challenged or exceeded during this event, notes the UK met office.
Climate scientist at Indiana University, Christopher Callahan, in a preliminary estimate, says June 2026 heatwave claimed lives of 20,000 people across Europe. His analysis shows the vast majority of the deaths likely occurred during the week of June 22-28, when temperatures peaked at above 40C across many countries. The greatest mortality was estimated in France with 5,210 deaths, Germany 4,543, Spain 3,163, and Italy 2,709.
Callahan’s analysis lays bare the fact of rapidly rising mortality risks when daily maximum temperatures increase. Days above 40C cause more than six per cent increase in weekly mortality rates compared with days around 25C.
Then he makes an important point about the surging temperatures and breakdown of whatever adaptation measures people took. From his paper: “In most cases, warmer regions in Europe appear less vulnerable to heat, consistent with evidence of adaptation—but this pattern reverses for days above 40C, with warmer regions experiencing greater mortality risk, potentially indicating fundamental limits to adaptation.”
In 2023, 48,000 people died in Europe due to heat between May and September; In 2022, 60,000 people died in Europe due to heat. The above-mentioned 20,000 deaths due to heat Callahan estimates is for one week: June 22-28. As heat is expected to be ongoing, the death numbers will only increase in the coming weeks and months.
Asked what the heat wave in Europe might mean for India which has also seen record heat waves, Callahan tells Hot Rock, “We do expect the impacts of heat to be greater in South Asia, and Asia in general, than in Europe.”
On the other hand, Europe is poorly adapted to heat because it has historically been quite cool.
“There are lots of populations in South Asia, such as outdoor labourers, who are extremely exposed to high temperatures and are quite vulnerable to heat-related illness. These populations will likely suffer the first impacts of rising temperatures,” he says.
The present heatwave conditions in Europe exceeded model estimations. “Models are underestimating warming in Europe because of specific changes in atmospheric circulation systems in the region, as well as some changes in air pollution concentrations. This doesn’t necessarily mean that models will get India wrong; Europe may just be a uniquely difficult region to model,” says Callahan.
According to the Copernicus Climate Change Service (C3S), Europe is the fastest-warming continent and has warmed by approximately 0.53C per decade since the mid-1990s, and the Arctic is warming even faster—around 0.69C per decade. In fact, India might actually be warming slightly slower than expected.
“This doesn’t mean we should be complacent about heat risks; extreme heat is still a major threat in the region,” says Callahan.
Using climate models, scientists convert emissions into hazards such as extreme heat and floods. “Uncertainty in climate model projections is inevitable, no matter how much science we do,” he tells Hot Rock. What is not inevitable, though, is relentless heat. In the first week of July, heat presided over the United States.
According to World Weather Attribution, climate change is a big player in the football World Cup, with the US, Canada, and Mexico as hosts. Matches are spread over 16 cities and the final will be held in New York on July 19. Due to concerns about heat and dehydration, the football’s governing body, FIFA, instituted three-minute hydration break in each half of matches.
So, where does all the heat come from?
The fact is, Callahan states in his paper, increasing extreme heat, and resulting mortality, is the consequence of global warming driven by fossil fuel emissions. Every tonne of CO2 emitted appreciably increases global average temperature and thus local heat extremes. Given the continued increase in fossil fuel emissions and the potential for extreme events even if humanity undertakes rapid decarbonisation, significant increases in adaptation investments will be necessary to reduce future heat mortality. Understanding which adaptations to heat are most empirically successful and can be scaled rapidly is thus a critical research priority.
So, Callahan tells Hot Rock, the most important actions we can take are: first, reducing greenhouse gas emissions, in order to reduce the future risk of more extreme heat; and second, increasing adaptation investments to allow people to survive deadly heat conditions. This means increasing air conditioning, heat early warning systems, comprehensive health care coverage, and other similar actions.
