Environment & Energy

The killer ‘omega block’ heat dome heading for Britain
Europe is trapped under a ‘pressure-cooker lid’ weather system shaped like the Greek letter

Henry Samuel
Paris Correspondent

Published 23 June 2026 4:22pm BST

Europe is simmering under an “omega block” heat dome, a massive ridge of high pressure that has locked itself over the Continent.

The weather system traps hot Saharan air beneath it like a lid on a pressure cooker.

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“Underneath that heat dome, where the air is trapped and the heat builds, so does pollution, and particularly ozone pollution... So not only have you got health issues because of the heat, you also have a health impact because of increased air pollution.”

She said “thousands” would die because of excess heat in the UK, and “probably tens of thousands across France” but noted that the deaths would not be reported in real time because the statistics would not appear “until maybe a month or a few months after the event, and so we call heat the silent killer”.

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10 June 2026
North Africa’s heatwaves are lasting longer, hitting harder
Scientists warn that extreme heat is increasingly colliding with drought, water stress and fragile urban systems.
By Mohammed El-Said

When Morocco issued an orange-level heat alert in late May 2026, temperatures were forecast to reach 44°C across parts of the country, including Laayoune, Dakhla, Smara, Tata, Tarfaya and Tan-Tan. Egypt had already endured its own early-season heat episode weeks earlier, with temperatures climbing above 40°C in several regions.

For scientists, these events signal a wider shift as the region is now experiencing hotter baselines, longer warm seasons, warmer nights and more persistent heatwaves, interacting with drought, water scarcity, urban growth and fragile health systems.

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The hidden toll of heat
The human consequences of the new normal are severe and often underestimated. Heat can kill directly through heatstroke, but it also exacerbatess cardiovascular, respiratory, kidney and metabolic diseases. Older people, infants, pregnant women, people with chronic illnesses, outdoor workers and residents of poorly ventilated or informal housing are especially vulnerable.

The World Health Organization warns that prolonged hot days and warm nights increase physiological stress, while heat can reduce labour productivity and interact with air pollution. Yet, many heat-related deaths are recorded under underlying diseases rather than heat itself, making the actual toll difficult to measure.

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