U.K. Declares National Emergency in Heat Wave

Bob Ward, the communications director of the Grantham Research Institute on Climate Change and the Environment, said temperatures like these are “well above anything we’ve ever seen before.”

Mr. Ward estimated that this week’s heat wave could result in 2,000 deaths. Last year—a year that, according to Mr. Ward, saw temperatures “nothing like we are seeing now”—1,600 people died as a result of heat waves in the U.K.

“The U.K. still struggles to deal with hot weather, and still thinks of itself as a cold country. Periods such as this show how vulnerable the country is,” he said.

The current record for the U.K. is 101.6 degrees Fahrenheit in July 2019.

Schools were let out early on Monday, summer camps closed and hospitals canceled routine appointments as they anticipated a surge in heat-related medical issues. The government boosted capacity for ambulance services and health systems to help them to respond, according to U.K. Health Secretary Steve Barclay.

Network Rail, which operates the country’s train network, urged customers to travel only if necessary, closing some railway lines and reducing the speed limits on others to prevent hot rails from buckling. The London Underground also reduced service on some of its lines, warning that high temperatures could affect equipment.

“Closing the line to traffic is always a last resort but it is the right thing to do to keep people safe on Tuesday given the unprecedented heat wave forecast,” said Sam MacDougall, operations director for Network Rail. “The forecast temperatures are well above those which our infrastructure is designed, and safety must come first.”

The extreme heat has caused disruption across U.K. airports, with the international London Luton Airport suspending all flights because of a surface defect on the airport’s single runway. “Extreme temperatures caused a small section of the runway to lift,” a Luton spokesperson said. Engineers were working on repairs and looking to resume flights as quickly as possible, the airport said.

The heat led the British Royal Air Force to halt flights to and from its biggest air base, Brize Norton. “During this period of extreme temperature flight safety remains our top priority, so aircraft are using alternative airfields in line with a long-established plan,” said a spokesperson at RAF.

The rest of Europe, particularly in the south, is also baking in record temperatures.

In recent days, wildfires have scorched countries in southern Europe, and thousands have been evacuated from their homes. The European Commission has deployed 11 planes from its firefighting fleet to four countries, responding to urgent requests for international assistance in Portugal, Albania, France and Slovenia.

“Extreme weather conditions and new emerging threats have stretched the ability of member states to help each other, especially when several member states face the same type of disaster simultaneously,” said Balazs Ujvari, a spokesman from the European Commission’s Humanitarian Aid and Crisis Management office.

Last week, temperatures reached 115 degrees in Portugal—the highest ever recorded by the Portuguese Institute of the Sea and Atmosphere—as thousands of firefighters battled 13 forest fires. The extreme heat has killed 659 people in the past week, according to the Portuguese Health Ministry.

In France’s southwest, firefighters were still struggling on Monday to contain wildfires raging out of control. Fires have destroyed more than 35,336 acres of pine forest over the past week in the Gironde region near the city of Bordeaux, forcing the evacuation of more than 16,000 people, including many who were spending their vacation at campsites, local authorities said. About 1,700 firefighters and nine water-dropping planes have been deployed across the area, they added.

Thick plumes of smoke could be seen close to the Dune of Pilat, the tallest sand dune in Europe and a popular tourist destination in the Arcachon Bay area.

The peak of this heat wave in France was expected on Monday, forecaster Météo-France said, predicting temperatures between 104 degrees and 107.6 degrees Fahrenheit.

“The day could become one of the hottest ever recorded in France,” it said. Temperatures in the Brittany port of Brest in the country’s northwest could edge toward an unprecedented 104 degrees, it said.

France has issued red alerts, the highest possible, for several regions, with residents urged to be extremely vigilant. There have been no reports of injuries so far.

Write to Elissa Miolene at elissa.miolene@wsj.com