CNN  — 

New records have been set as temperatures topped 40 degrees Celsius (104 degrees Fahrenheit) across much of Spain and Portugal Wednesday amid a persistent heat wave across western Europe.

In northwest Spain, the city of Ourense set its all-time temperature record of 43.2 degrees Celsius (109.76 degrees Fahrenheit) on Tuesday, according to Spain’s meteorological agency, AEMET.

On Wednesday, Zamora set its own record after reaching 41.1 degrees Celsius (105.98 degrees Fahrenheit), according to climate statistician Max Herrera. Soria set a record of 38.7 degrees Celsius (101.66 degrees Fahrenheit) that same day.

The central Portuguese town of Lousã set an all-time record of 46.3 degrees Celsius (115.34 degrees Fahrenheit) and Lisbon set a July record of 41.4 degrees Celsius (106.52 degrees Fahrenheit).

But the worst is yet to come.

Spain and Portugal brace themselves

People cool off with a fountain's water during a heat wave in Seville, Spain on July 12.

Officials in Spain and Portugal are bracing themselves for the hottest day of the heat wave so far.

Temperatures are set to reach around 45 degrees Celsius (113 degrees Fahrenheit) in parts of western and southern Spain, according to AEMET. In its afternoon update, AEMET warned that Spain is set to experience its hottest day of the heat wave on Thursday.

Similar is being said of Portugal. Portuguese Prime Minister Antonio Costa told reporters that Thursday is set to be the “most serious day” for Portugal as far as the extreme weather is concerned, warning that the country needs “to be more careful than ever to avoid new occurrences.”

Eight out of the country’s 18 mainland districts have been placed under a red weather warning by the Portuguese Institute for the Sea and Atmosphere (IPMA).

In light of the heightened risk, the country’s “state of alarm” is set to be extended until Sunday, Costa added.

A member of the armed forces walks near a forest fire in Palmela, Portugal on July 13. The fire is currently close to a petrol station. In an effort to save their lives, some people and animals are being evacuated.

Portugal continues to be one of the countries hardest hit by the current heat wave across western Europe. There are currently 1,656 firefighters fighting the 10 active rural fires across Portugal, the Portuguese Civil Protection Services said Thursday.

More than 7,400 acres of forest have been burned in the Leiria district in central Portugal, according to the municipality of Leiria.

Thousands evacuated due to wildfires

France is in a similar predicament. Since Tuesday, more than 6,500 people have been evacuated from their homes and campsites as wildfires rage in the country’s southwestern regions, according to regional police on Thursday.

More than 9,000 acres have been destroyed by two large forest fires in the Gironde department, according to a statement published by the department’s police.

A wildfire burns through vegetation in Landiras, southwestern France, on July 13.

Around 1,000 firefighters from local and national brigades have been mobilized since Tuesday to stop the spread of the fires. Six water bomber planes are also being used.

Grégory Allione, president of the national federation of firefighters, called on towns around the country to cancel their traditional Bastille Day firework displays, speaking on French channel Franceinfo on Thursday.

“What is responsible, is to cancel them, what is responsible is to take into account that we are in a period of drought, of heat waves,” Allione said, adding that the fires “are still evolving, we expect to face difficulties today given the rise in temperature and the whirling winds.”

Firefighters work to extinguish a wildfire which broke out at the bottom of the Dune du Pilat near Teste-de-Buch, southwestern France on July 13.

During a visit to the area on Wednesday, Interior Minister Gérald Darmanin told journalists that authorities “were on very high alert in the coming days, especially in the south of France.”

The UK is next

The peak of the heat is occurring now across the Iberian Peninsula, and is set to spread to the north and east in the coming days.

A “rare” amber extreme heat warning issued by the UK Met Office for Sunday, July 17, has been extended to Monday and Tuesday, when temperatures are expected to be in the mid 30s.

The UK’s record high temperature is 38.7 degrees Celsius (101.7 degrees Fahrenheit), which could be surpassed, according to the Met Office.

“Some models have been producing maximum temperatures in excess of 40 degrees Celsius (104 degrees Fahrenheit) in parts of the UK over the coming weekend and beyond,” the Met Office’s Rebekah Sherwin said.

“Population-wide adverse health effects are likely to be experienced, not limited to those most vulnerable to extreme heat, leading to potential serious illness or danger to life,” the Met Office said. “Significantly more people are likely to visit coastal areas, lakes and rivers leading to increased risk of water safety incidents.”

The UK could also experience road closures due to melting surfaces, as well as delays to rail and air travel in the thick of the extreme heat.

CNN’s Brandon Miller contributed reporting.