A severe heat wave swept across Europe on Thursday, putting all major Italian cities under the highest heat alert while Austria and Slovakia recorded their highest-ever temperatures.
Temperatures climbed above 40°C (104°F) in several countries, raising health concerns for millions and putting pressure on power supplies, transport networks and public services.
Scientists and officials said increasingly frequent and intense heat waves are linked to a warming climate and are forcing governments to prepare for more extreme weather.
Italy issues red alert across all major cities
Italy's Health Ministry placed all 27 cities covered by its heat monitoring system under a red alert Thursday, marking the first time this year that the entire network has simultaneously reached the highest warning level.
The alert covers cities from Trieste in the northeast to Palermo in Sicily and indicates a health risk for everyone, not just older people and those with existing health problems.
Authorities advised people to avoid direct sunlight during the hottest part of the day, stay indoors when possible and drink plenty of water.
The heat wave has also led to changes at major tourist sites. The tourism and culture ministries extended evening opening hours at attractions including Rome's Colosseum and Pantheon.
Cooling mist fans were installed at Colosseum entrances, while additional medical stations were set up to help visitors cope with the heat.
Rome has also opened a free temporary "urban beach" along the Tiber River in the Marconi area. The Tiberis site offers swimming pools, water fountains and shaded spaces, providing residents and children with a place to escape the heat.
Austria, Slovakia record highest-ever temperatures
Slovakia recorded a new national temperature record Thursday, with the mercury reaching 42.2°C (108°F) at Dolne Plachtince in the south, according to the Slovak Meteorological Institute.
Low water levels in the Danube have also affected the country's biggest hydroelectric power plant in Gabčíkovo. Seven of its eight turbines were shut down, with the plant producing 15% less electricity this year than during the same period last year.
The Academy of Sciences said the Danube recorded its lowest July water flow on record.
Austria recorded its highest-ever temperature on Wednesday, reaching 41.2°C (106.2°F) in Bad Deutsch-Altenburg near the Slovak border, according to GeoSphere Austria.
The country is also experiencing severe drought. Rainfall during the first six months of the year was 27% below the long-term average nationwide, while some eastern areas received only half their normal rainfall.
Climatologist Alexander Orlik said some parts of Austria had not seen such dry conditions since 1885.
Hungary cuts power use amid drought
Hungary's prolonged drought and record-low Danube levels have affected its only nuclear power plant, which depends on river water to cool its reactors.
The plant has cut production to around 10% of normal levels, prompting the government to introduce emergency measures to reduce electricity use.
Authorities asked industries and households to limit power consumption, particularly between 5pm and 10pm, when demand is highest. Freight trains have also been banned from operating during those hours, while decorative lighting at Budapest landmarks has been switched off.
Major companies, including energy firm Mol, pharmaceutical company Gedeon Richter and automakers Suzuki, Mercedes-Benz, Audi and BMW, have announced plans to reduce electricity consumption.
The government also canceled parliamentary sessions this week as part of efforts to save power.
Budapest recorded its hottest night on record Wednesday, with the temperature dropping only to 28°C (82°F).
Germany concerned over falling river levels
Germany is increasingly concerned about the effects of drought on transport and industry as water levels in the Rhine and other rivers continue to fall.
Transport Minister Steffen Bilger met with affected organizations Thursday and said low river levels were creating serious problems for inland shipping, industries and the wider supply chain.
Environmental group BUND called for measures to make rivers more resilient to climate change, including retaining more water in the landscape and reducing water withdrawals during droughts.
France remains at high wildfire risk
Firefighters continued to monitor the Var region in southeastern France after authorities said a major wildfire was no longer spreading but could flare up again.
The fire, which started on July 20, has burned more than 60 square kilometers (23 square miles), making it the largest wildfire recorded in the region in recent decades.
Authorities warned that strong winds and extremely dry conditions were keeping the wildfire risk very high across southeastern France.
In England, temperatures eased, but the effects of the country's driest July on record remained visible. A grass fire temporarily closed the southern runway at London's Heathrow Airport on Thursday.
Balkans battle wildfires and drought
The heat wave peaked across the Balkans on Thursday, with temperatures approaching 40°C (104°F) as countries struggled with drought and wildfires.
Firefighters in Serbia battled several blazes after days of dry weather. One major fire spread through pine forests west of Belgrade, while another broke out near Kraljevo in central Serbia, where difficult terrain hampered firefighting efforts.
In neighboring Croatia, tourists in Dubrovnik sought shade and avoided the beaches during the hottest hours as temperatures soared along the Adriatic coast.