The World Health Organization’s European director warned on Tuesday that a new heatwave forming over the Atlantic could bring “lethal weeks” to the continent, as temperatures in parts of Spain and Portugal are expected to hit 43°C this week. The alert came as Italy’s health ministry raised heat-risk levels to orange—the second-highest tier—in ten cities, with Florence set to reach red alert on Thursday. The UK Met Office confirmed that south-east England had already met heatwave criteria, and amber heat-health alerts were issued for the Midlands and southern England. This is the third major heatwave of the year for many European countries, following record-breaking heat in June that caused thousands of excess deaths.

The heat is driven by a strong African anticyclone pushing hot air northward, a pattern that climate scientists say is becoming more frequent and intense due to human-caused warming. The Mediterranean Sea has already reached unprecedented temperatures for late June, up to 2.6°C above normal, according to Spain’s meteorological agency. In Germany, meteorologists described the situation as catastrophic, with historic drought conditions killing fish, fuelling wildfires, and prompting warnings of a “shit summer” from prominent forecasters. The UK also faces a parallel marine heatwave, with sea surface temperatures up to 5°C above average off southern and eastern coasts, threatening mass die-offs of seagrass and shellfish.

Infrastructure built for a cooler climate is buckling. Rail operators in the UK urged passengers to travel only if essential, as steel rails risk warping and overhead wires sag. East Midlands Railway suspended some regional services from midday, while Great Western Railway imposed speed restrictions. Across Europe, roads are softening and traffic systems malfunctioning. Analysts in London note that the continent’s next major infrastructure spending cycle may shift from decarbonisation to heat-proofing: demand is rising for polymer-modified asphalt, concrete sleepers, and robust rail fastening systems. Companies such as TotalEnergies, Shell, and Vossloh are positioned to benefit as governments confront the cost of adapting legacy networks to new temperature extremes.

The WHO stressed that fewer than half of its European member states have comprehensive heat-health action plans, leaving millions of elderly and vulnerable people exposed. The June heatwave caused an estimated 3,700 excess deaths in France, the Netherlands, and Belgium alone. With the current heatwave expected to persist well beyond 10 July—Italy’s Po Valley could reach 39°C and Sardinia 40°C by the weekend—the immediate test is whether national and local authorities can rapidly deploy cooling centres and enforce heat-safety protocols. The WHO is convening emergency meetings with 41 countries to share lessons from the previous event. The next milestone will be the extent to which governments accelerate adaptation funding to match the scale of the threat before peak temperatures arrive.