Yvonne, the high-pressure hot air mass that is grilling Europe, has lifted surface air temperatures in Germany beyond 40 C (105 Fahrenheit) and left France bracing for up to 42 C on Thursday.

Germany recorded a probable record high of 40.5 C in Geilenkirchen in North Rhine-Westphalia state, which if confirmed would top the previous high of 40.3 C recorded in Bavaria in 2015. The reading, reported by Germany's DWD weather service, was not taken at one of its own measuring stations, but one operated by NATO and was being checked, a DWD meterologist told German news agency DPA.

Dutch and Belgian meteorological services recorded similar peaks around 39 C on Wednesday, beating their record temperatures documented in the 1940s.

Brussels authorities reduced the hours of staff working outside. Pairi Daiza zoo in western Belgium fed iced chickens to tigers, and watermelons, also encased in ice, to bears.

'Tropical' nighttime temperatures

Even overnight temperatures will barely drop below 24 Cs in Germany's hot spots, such as its Ruhr District and the Rhine-Main region around Frankfurt, according to the DWD. The service issued peak heat warnings for Thursday.

Read more: Germany records all-time hottest June

The DWD said Yvonne stretched from the central Mediterranean to Scandinavia and hung like a "bell" over Europe, pinned between two low-pressure zones — one over western Russia and the other over the eastern Atlantic.

Bonn, Germany's former capital, saw the mercury hit 39.2 C — alongside a still navigable but shrinking Rhine River.

Low water already crippling the Danube in Bavaria prompted river officials on Wednesday to bar hotel ships from using a 60-kilometer (39-mile) stretch upstream from Vilshofen. Tributary residents were banned from extracting water.

France braced for 42 degrees

In its forecast for Thursday, France's weather service predicted between 37 C and 42 C — conditions likely to break Paris' heat record set in 1947.

Water-usage restrictions are in place in 73 out of France's 96 mainland departments, notably the Loire region.

France's SNCF rail service, fearing faults because of the "exceptional weather conditions," urged passengers to delay trips, offered them refunds and said its high-speed trains would run slower. Britain's Network Rail said it was slowing trains, too.

Cooling off at Tuesday's finish line in Nimes

At cycling's heat-plagued Tour de France, team doctors said athletes were at the limit of how much water they could drink to compensate for dehydration.

Appeals to avoid heatstroke

Berlin's mayor Michael Müller and France's Prime Minister Edouard Philippe each issued public appeals for residents to watch out for vulnerable elderly and homeless people.

"We need to take care of ourselves, but above all others, especially those who are alone, and be able to detect the first symptoms of heatstroke," said Philippe, referring to France's 2003 heat wave which claimed thousands of lives.

Berlin's Müller urged residents not to leave home without a bottle of water and to donate this to homeless persons they met.

"Living on the street on days of exceptional heat harbors special dangers for persons who are homeless," said Müller.

Heat trends matches calculations

Climate researcher at Britain's University of Reading Peter Innes said the increased frequency of hot summers matched calculations about man-made global warming.

"It has been estimated that about 35,000 people died as a result of the European heat wave in 2003, so this is not a trivial issue," said Innes.

Managers at rest homes in Hamburg — applying hot-weather experience gained in recent years — said their elderly residents were being encouraged to drink plenty and, if necessary, use cold compression wraps.

Watch out for thirsty animals

Animal care advocates in Germany's southwestern Baden-Württemberg (BW) state urged the public to watch out for grazing horses, cattle and sheep left without sufficient water and shade.

Public watch urged for animals exposed to heat

"If necessary, one should have also no qualms about reporting obviously thirsty animals and long-empty watering devices to the [local] veterinary office responsible for animal protection," said Stefan Hitzler of BW's animal welfare association.

Dortmund police said three pigs had already died of dehydration on board a truck en route from France to a slaughter plant in Germany. The police were notified by a watchful motorist. The rest of the 143 animals on board were given water. The driver was fined.

Belgian beekeeping federation president Bruneau Etienne said bees risked dehydration, because in hot weather they preferred to stay inside hives.

Four degrees hotter

Europe's first 2019 heat wave that occurred between June 26-28 was later described by the World Weather Attribution (WWA) project team as being 4 C hotter than an equally rare June heat wave would have been in 1900

Another study by the Swiss Federal Institute of Technology said last year's weekslong heat wave across northern Europe in 2018 would have been statistically impossible without climate change.

ipj/rc (dpa, AFP, Reuters, AP)