Fire weather in the EU has broken records for severity for this time of year, data shows, as firefighters race to extinguish blazes across the Mediterranean.

Inflamed by carbon pollution, the hot, dry and windy weather across the EU from the start of the year until the end of July has been 43% more severe than the average for the same period over the last two decades, data from the European Forest Fire Information Service (Effis) shows.

Three firefighters died in Greece on Tuesday, officials said, while firefighters in France and Spain made overnight progress tackling monster blazes that have burned dangerously close to large cities.

The figures, which were published on Thursday but may be revised further, showed that so far this year 435,000 hectares (1,075,000 acres) have burned, roughly triple the recent historical average. The devastation is the result of 1,400 fires, more than double the average.

In France, where a blaze in the dense pine forests near Bordeaux grew so big it generated a rare thunderstorm that could ignite more fires, a total of 91,000 hectares have burned, according to Effis, breaking the country’s record for a full year of fires – with one month of summer still to go.

Fire-ravaged south-western France experienced its “first somewhat optimistic day” on Thursday since wildfires broke out more than a week ago, said Sophie Brocas, the prefect of Gironde. “It is the first somewhat optimistic day, because we have the feeling that we are beginning to return to normal life and that things are starting to improve significantly.”

Regional authorities in Gironde said the fire remained under control after a quiet night, with work continuing around its edge and in active hotspots. They said temperatures on Thursday had been expected to be “fairly favourable” after Wednesday’s 38C heat and strong winds hampered firefighting efforts.

They allowed a further 84,000 people to return home on Thursday, after 60,000 people were given the green light on Tuesday.

In Spain, which experienced its largest wildfire on record, west of Madrid, a total of 207,000 hectares have burned across the country, according to Effis. The figure is nearly five times the average for this time of year but shy of the devastation reached by late July during the 2022 fires.

Regional authorities in Madrid said the fire situation had been declared “stable” but residents of seven housing estates were unable to return home. Pedro Sánchez, the prime minister, announced the end of the national emergency in the regions of Ávila and Madrid on Thursday morning.

However, a new fire near the Portuguese border prompted the evacuation of 600 people, officials said. Aemet, the Spanish meteorological agency, said temperatures above 35C were expected on Thursday in large areas of the interior, with some regions bracing for highs of 40C-42C.

Wildfires in France and Spain have forced more than 300,000 people from their homes and tourist accommodation this month, prompting both countries to request EU support in the form of firefighters, fire engines, and water-dropping planes and helicopters.

Ursula von der Leyen, the president of the European Commission, thanked firefighters for their “courage and commitment” on Wednesday as crews sent by Romania and Greece extended their stays. “As the fires in France and Spain continue to ravage, European solidarity knows no limit,” she said.

Further difficult weeks were expected as fires worsened in Italy and Greece, officials at the EU’s crisis management centre said on Wednesday morning. Later that day, the Greek fire department announced the deaths of two firefighters who were tackling a blaze on the island of Crete, and of another in the south of the mainland.

Greece has so far had a relatively calm fire season, Effis data up to 29 July shows, with slightly fewer fires than usual and a burned area well below the average.

Meanwhile, Italy and Portugal have had near-record breaking numbers of fires, and burned areas well above average. The countries have so far been spared the scale of destruction experienced by France and Spain, but one firefighter died in Italy last week while tackling blazes in Sicily.

Climate breakdown is causing Europe to burn this summer, with a series of almost back-to-back heatwaves drying out vegetation, which then provides a vast fuel surplus that has allowed small fires to grow into raging infernos.

Sánchez repeated calls to create a “national pact” to address the climate emergency during a visit to a command post on Wednesday.

“These fires may or may not be caused by humans, but in any case, they increase exponentially as a result of these high temperatures, low humidity, and also the atmospheric phenomena that these fires, these large fires, cause in our forests,” he said.

A study by an international team of scientists, published in the journal Scientific Reports, found that since the 1980s, the number of fires in southern Europe and the area burned had steadily declined as authorities became better at preventing and suppressing them.

The study, published on Thursday, found the trend began to reverse in 2018. It found that summer days conducive to strong wildfires had more than doubled since 1981 across large parts of Portugal, Spain, France, Italy and Greece; in parts of France and Spain, the summertime fire weather index over the last decade was up to 50% higher than the 1981-2010 average.

The scientists said this had resulted in European fires shifting to “fewer, but more intense and larger events”, with fires that escaped initial attacks by firefighters able to “quickly become catastrophic”.

José Miguel Viñas, a meteorologist at the forecaster Meteored, who was not involved in the research, said it scientifically demonstrated a fact that southern Europe and other parts of the world had observed in recent years.

“Increasingly extreme conditions of heat, dryness and wind are fuelling large forest fires,” he said. “Once started, they spread rapidly and become uncontrollable, overwhelming the firefighting efforts.”

Rapid analyses have found western Europe’s June heatwave would have been “virtually impossible” in a world without climate breakdown, while the level of soil dryness – a major factor in bigger blazes – is five times more likely than it would be in a climate 1.4C cooler. The heatwaves are estimated to have killed at least 10,000 people and cost grain farmers €2bn (£1.7bn) in lost crops.

The increase in temperatures from fossil fuel pollution has come as rural regions in southern Europe have hollowed out, with farms being abandoned as populations age and young people move to cities. The resultant overgrowth in vegetation has troubled firefighters and wildfire researchers across the Mediterranean.