PARIS, France — A record-breaking heatwave sweeping across Europe has pushed temperatures to 40 degrees Celsius (104 degrees Fahrenheit) in several areas, disrupted transport and power systems, strained healthcare services, and prompted France to warn that the number of heat-related deaths could increase as authorities complete their assessments.

France’s public health agency reported around 1,000 excess deaths during the extreme heat event, with most fatalities involving older people. Officials said the figure may rise as more information becomes available from residential care facilities and private homes where heat-related deaths are still being reviewed.

The heatwave, which began on June 20, has been described by scientists as among the most severe recorded in Europe. Researchers said the intensity of the extreme temperatures would have been highly unlikely without human-driven climate change, which has increased the frequency and severity of prolonged heat events.

World Health Organization Director-General Tedros Adhanom Ghebreyesus said the crisis showed the growing impact of extreme heat on communities across the continent.

“Right now 150 million people are living under extreme heat, hundreds have died, schools are shut, grids are buckling,” Tedros wrote on X, warning that climate change has turned once-rare heat events into increasingly common occurrences.

The extreme temperatures affected several countries, with record heat reported in Austria, the Czech Republic, Germany and Poland. Storms also hit parts of France, creating additional challenges for transportation networks and electricity supplies.

In Germany, rail services were reduced along a major route in North Rhine-Westphalia, while tram operations were suspended in Leipzig. Many residents stayed indoors during the hottest hours of the day as authorities urged people to avoid unnecessary exposure to the heat.

The heat also disrupted Europe’s energy and agricultural systems. Rivers that provide cooling water for power plants experienced higher temperatures and lower flows, creating operational difficulties.

In Hungary, the Paks nuclear power plant reduced electricity production because the Danube River, which supplies cooling water for the facility, became too warm. Officials said the adjustment was necessary to manage the impact of rising water temperatures.

In Italy, the Po River’s declining flow allowed seawater to move inland as far as 18 kilometers, raising concerns about farmland and protected wetlands in the river delta. The country also reported several drowning incidents involving people seeking relief from the heat.

Authorities across Europe continued issuing public health warnings. In the Czech Republic, officials advised residents to avoid strenuous physical activity and issued smog alerts in central and northern areas because high temperatures contributed to increased ground-level ozone levels.

France experienced some relief as cooler air moved in following thunderstorms, but the weather system caused further disruption. Electricity provider Enedis reported that about 36,000 households in northern and central France remained without power on Sunday afternoon following the storms.

France’s weather agency said extreme heat had eased in most parts of the country, although some northeastern areas remained under heat advisories. Health Minister Stéphanie Rist warned that the health effects of the heatwave could continue for days even after temperatures decline.

“The episode is not finished,” Rist told broadcaster BFM, adding that the impact of extreme heat may continue for up to 10 days after conditions improve.

Meteorologists said thunderstorms could affect parts of France, Germany and the Czech Republic in the coming days, while cooler weather was expected across much of Western Europe. However, the heatwave was forecast to continue moving toward Central Europe and the Balkans.

The European heatwave has renewed concerns over the continent’s preparedness for increasingly frequent extreme weather events, as governments face growing pressure to strengthen public infrastructure, emergency response systems and climate adaptation measures.