A relentless heat wave continued to batter Europe on Thursday, pushing temperatures above 40 degrees Celsius (104 Fahrenheit) in multiple countries and triggering a cascade of disruptions across public health systems, energy infrastructure, transportation networks, and tourism. The event is the latest in a pattern of intensifying summer heat extremes that have struck the continent in recent years, including record-breaking waves in 2022 and 2023 that each caused thousands of excess deaths across Southern and Western Europe.

Italy's Health Ministry placed all 27 cities monitored under its national heat surveillance system on red alert — the first time this year that the entire network has simultaneously been at the highest warning level. The alerts, stretching from Trieste in the northeast to Palermo in Sicily, signal a health risk for the entire population, not just vulnerable groups such as the elderly or those with chronic illnesses. Authorities urged residents and visitors to avoid direct sunlight during peak heat hours, remain indoors where possible, and stay hydrated.

The extreme heat also prompted adjustments at major tourist sites. Italy's ministries of tourism and culture extended evening opening hours at landmarks including Rome's Colosseum and Pantheon. Cooling mist fans were installed at the Colosseum's entrances, and additional medical stations were made available on-site.

Austria recorded the most extreme temperature of the event so far. According to GeoSphere Austria, the mercury reached 41.2 C (106.2 F) on Wednesday in the village of Bad Deutsch-Altenburg, near the Slovak border — the highest temperature ever recorded in the country. Austria is simultaneously experiencing severe drought. Rainfall from January 1 through June 30 was 27% below the long-term national average, with some eastern regions receiving only half their normal precipitation. Climatologist Alexander Orlik noted that parts of the country had not seen such dry conditions since 1885.

In Hungary, prolonged drought and record-low water levels on the Danube River have severely impacted the country's only nuclear power plant, Paks, which depends on river water to cool its reactors. The plant typically supplies roughly half of Hungary's electricity, making the output reduction especially consequential for the national grid. Plant operators have reduced output to approximately 10% of normal production, prompting the government to introduce emergency conservation measures.

Authorities have called on major industrial users and households to curtail electricity consumption, particularly during peak demand hours between 5 p.m. and 10 p.m. Freight trains have been barred from operating during those hours, and decorative lighting on landmarks in Budapest has been switched off. Several major companies — including energy company Mol, pharmaceutical maker Gedeon Richter, and automakers Suzuki, Mercedes-Benz, Audi, and BMW — have announced plans to reduce electricity use. The government also canceled parliamentary sessions this week to conserve power.

The heat wave has shattered records across Hungary. On Wednesday night, Budapest recorded its warmest overnight low temperature on record, with the mercury falling only to 28 C (82 F), underscoring the persistence of the extreme conditions. High overnight temperatures are a particular public health concern because they prevent the body from recovering from daytime heat exposure, a factor epidemiologists link to elevated mortality during prolonged heat events.

Germany is facing mounting concerns over the impact of drought on transportation and industry as water levels on the Rhine and other rivers continue to drop. The Rhine is one of Europe's most important freight arteries, carrying commodities such as coal, chemicals, grain, and automotive parts; when water levels fall, barges must reduce cargo loads, raising shipping costs and disrupting supply chains. The river faced similar disruptions during droughts in 2018 and 2022. Transport Minister Steffen Bilger met with affected organizations Thursday and warned that low water levels pose major challenges for inland waterway shipping, industry, and the broader logistics chain. Environmental group BUND urged authorities to look beyond economic impacts and focus on making rivers more resilient to climate change by retaining more water in landscapes and reducing withdrawals during drought periods.

In southeastern France, firefighters maintained a significant presence in the Var region after authorities reported that a major wildfire there was no longer spreading but remained capable of reigniting. The blaze, which began July 20, has burned more than 60 square kilometers (23 square miles), making it the largest recorded wildfire in the region in recent decades. Authorities warned that strong winds and extremely dry conditions left southeastern France at very high risk for additional fires.

The heat wave peaked across the Balkans on Thursday, with temperatures nearing 40 C (104 F) and authorities battling drought and wildfires. In Serbia, firefighters struggled to contain several blazes following days of dry weather. One major fire burned through pine forests west of Belgrade, while another spread near the central town of Kraljevo, where difficult terrain hampered firefighting efforts. In neighboring Croatia, tourists in Dubrovnik sought shade and avoided beaches during the hottest hours as temperatures soared along the Adriatic coast.

Scientists and officials warn that such extreme events are becoming more frequent and intense as the climate warms. From the Mediterranean to Central Europe, prolonged heat, drought, and wildfire conditions are increasingly defining features of summer, exposing vulnerabilities across critical infrastructure — from nuclear cooling systems to inland shipping routes — and forcing governments and businesses to adapt.

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Associated Press journalists Sylvie Corbet in Paris, Jovana Gec in Belgrade, Serbia, and Karel Janicek in Prague contributed to this report.

This story was originally featured on Fortune.com.