Two atmospheric patterns may explain why some heat waves in Europe persist
Many parts of Western Europe are currently wilting under a heat wave. These blistering spells can last for a week or more, and although they are common in most summers, it is difficult to predict how ...
Many parts of Western Europe are currently wilting under a heat wave. These blistering spells can last for a week or more, and although they are common in most summers, it is difficult to predict how long they will last.
Heat that persists for prolonged periods can be more dangerous than short bursts of a few days because it puts people's bodies and infrastructure under stress for longer, not to mention the potential for severe drought and crop losses.
One reason these prolonged weather events are so difficult to predict is that they depend on complex atmospheric processes over long timescales. Scientists also have only around 20 real-world examples of very long-lasting heat waves (lasting 12 to 26 days) in observational records to study.
In a paper published in Environmental Research Letters, scientists identified two common atmospheric circulation patterns associated with persistent heat over Europe. Recognizing these could help improve long-range heat predictions.
Simulating past summers
To bypass the lack of data, Duncan Pappert and Olivia Martius at the University of Bern in Switzerland used 150 years of historical climate simulations from a powerful climate model called the Community Earth System Model version 2 (CESM2). Across 50 simulations, researchers identified 1,884 virtual long-lasting hot spells to study.
They found two different atmospheric pathways associated with persistent summer heat in Western Europe, writing in their paper, "Persistent hot spells in Western Europe can be interpreted through two dominant circulation tendencies."
In the Type I pathway, high-altitude atmospheric waves travel across the Atlantic, helping to build and repeatedly reinforce a persistent high-pressure system over Europe. This acts like a giant lid, squeezing the air downward and trapping the heat beneath it.
In Type II, the jet stream shifts farther north, pushing storms away from Europe. At the same time, large bends in the jet stream help maintain a broad high-pressure system over Europe, trapping hot air over the continent.
"These two circulation patterns create the potential for hot spell persistence," added the research team. "The day-to-day evolution of these events is multifaceted and complex."
What happens on the ground is just as important. According to the paper, dry soils can also help prolong hot spells. Usually, some solar energy evaporates moisture from the ground, but when the soil dries out, more of that energy goes into heating the air instead.
Improving predictions
Understanding what is happening above us will be even more important in the coming years as summer heat waves become more frequent and intense. And while computer models are not a perfect mirror of reality, research like this can help scientists better understand why some hot spells persist. It may also eventually contribute to long-range forecasts, helping us better prepare for future heat waves.
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Publication details
Duncan Pappert et al, A tale of two hot spells: dominant circulation patterns favouring persistent high temperatures in western Europe, Environmental Research Letters (2026). DOI: 10.1088/1748-9326/ae7f34
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Citation: Two atmospheric patterns may explain why some heat waves in Europe persist (2026, July 14) retrieved 14 July 2026 from https://phys.org/news/2026-07-atmospheric-patterns-europe-persist.html
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