by Bob Henson, Yale Climate Connections
June 22, 2026

Europe’s worst heat tends to strike in July and August, but this week a startlingly early and intense heat wave is tossing the calendar aside. Temperatures could hit 100 degrees Fahrenheit (38 degrees Celsius) in London and 104°F (40°C) in Paris – not just once, but perhaps for two or three days in a row.

This isn’t the proverbial “dry heat.” In many spots, the humidity will be relatively high, which could lead to some of the most dangerously high heat indexes several countries have ever recorded. And heat waves like this one are getting more common as the climate changes, causing life-threatening conditions for Europeans who lack air conditioning.

Scorching heat set in across the Iberian Peninsula over the weekend and continued on Monday. Even though Spain is normally quite hot by late June, this heat wave is going a step beyond. In Madrid, readings on Tuesday may challenge the city’s all-time high of 40.7°C (105.3°F), which has been reached in June, July, and August.

On the north coast of Spain, the tourist haven of Bilbao is normally protected from the heat of Spain’s interior by the Basque Mountains to the south and the Atlantic to the north. Bilbao’s average daytime highs are only in the 70s Fahrenheit all summer. But on Sunday, hot southerly winds from Africa pushed over the Basque Mountains, heating even more as they flowed downslope. The result: a high in Bilbao of 43°C (109.4°F), which is hotter than any temperature ever recorded there outside of August.

Record heat for June is widespread across France

A sprawling upper-level high will park itself over France for much of the week, helping to keep French skies clear and the air descending and heating. Several drownings were reported in France on Sunday as people sought relief from temperatures that set records for June at more than 180 locations, as well as several all-time records above 40°C (104°F).

Even hotter readings are possible on Monday and Tuesday. The French government issued nationwide bans on public drinking of alcohol, and a record-high 35 out of 96 mainland French regions were placed under “danger-to-life” red alerts, the UK Guardian reported.

Torrid days and tropical nights in England

As the upper-level high elongates northward, the British Isles will find themselves under the heat gun as well. On Monday, the UK Met Office issued a Red Extreme Heat Warning – only the second such warning issued in British history – for Wednesday and Thursday. It covers most of southern England and eastern Wales, including the London area. The Met Office expects the nation’s all-time record high for June of 35.6°C (96.1°F) to be shattered, with readings above 39°C (102°F) likely.

Adding to the misery and hazard, dew point temperatures – which correspond to a fixed amount of moisture in the air – could reach 72°F (22°C), the Met Office said. That’s a common value on a sultry summer day in the eastern United States but extremely unusual for England. The moisture will not only intensify heat stress by day but also limit the amount of relief possible at night. The Met Office warned of widespread “tropical nights,” meaning those where the low fails to dip below 68°F (20°C). Again, that’s something familiar to most Americans east of the Great Plains but exceedingly rare in the UK, where air conditioning is still far from ubiquitous.

The UK’s last heat wave of this intensity struck in July 2022, when readings topped out at 40.3°C, exceeding 40°C (104°F) for the first time in British history and triggering the first-ever Red Extreme Heat Warning. The UK Health Security Agency estimated that the July heat wave together with four others in 2022 led to between 2,258 and 3,712 excess deaths, meaning fatalities beyond what would have been otherwise expected in that time frame.

Here’s one nugget of perspective on our warming climate: No official temperature in more than a century of UK weather monitoring had managed to reach 100°F before the catastrophic heat wave of August 2003. Since then, that temperature has been topped several times at multiple locations.

By late this week, the upper high and associated extreme heat will shift eastward into central Europe, perhaps pushing readings above 100°F (38°C) across many areas from Germany south to Italy and eastward from Poland to Hungary.

Climate change is making impossible and improbable heat waves a reality

Extreme heat is among the most-studied consequences of human-caused climate change, and the connections between a warming planet and amplified, localized extreme heat are not only intuitive but well documented. Among the findings from the nonprofit research initiative World Weather Attribution on European heat extremes from recent years:

Last year, a Call to Action on Extreme Heat was issued by the United Nations Secretary General António Guterres, building on an unprecedented teaming-up of 10 UN specialized agencies that included the World Health Organization and World Meteorological Organization. “More than 70 per cent of the global workforce – 2.4 billion people – are now at high risk of extreme heat,” the UN warned.

Perhaps surprisingly, cold-related deaths remain about nine times more common globally than heat-related deaths, as discussed in a 2025 overview in The Lancet Planetary Health. But in this case, the trend is the big issue, and it’s not our friend: Even a small rise in average temperature tends to increase heat deaths much more sharply than it reduces cold deaths. A 2025 analysis in Nature Medicine of projected temperature-related mortality trends under multiple scenarios for 854 European cities found that “with no adaptation to heat, the increase in heat-related deaths consistently exceeds any decrease in cold-related deaths across all considered scenarios in Europe.”

Irene Sans and Jeff Masters contributed to this report.

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