The United Kingdom has recorded its highest ever temperature as a fierce heatwave leaves much of western Europe sweltering, fuelling ferocious wildfires and stretching emergency services.

After UK's warmest night on record, the country's Met Office registered a provisional reading of 40.2 degrees Celsius (104.4 degrees Fahrenheit) at Heathrow Airport on Tuesday, breaching the 40C mark for the first time.

"Temperatures are likely to rise further through today," the Met Office meteorological agency added. Before Tuesday, the highest temperature recorded in Britain was 38.7 C (101.7 F), a record set in 2019.

The high temperatures have triggered an unprecedented red alert for extreme heat in much of England and Wales, where some rail lines were closed as a precaution and schools shuttered in some areas.

Experts blame climate change for the latest heatwave and note the more frequent extreme weather will only worsen in years to come.

World Meteorological Organization Secretary-General Petteri Taalas expressed hope that the heat would serve as a “wake-up call” for governments and voters to do more on climate change.

The WMO warned that temperatures may remain above normal into the middle of next week, adding that such events could occur with greater frequency in the future.

Wildfires and scorching temperatures across Europe

The heatwave, the second to engulf parts of Europe in recent weeks, has contributed to deadly wildfires in France, Greece, Portugal and Spain, destroying vast tracts of land.

Record high temperatures were registered in 64 different areas around France on Monday as a heatwave peaked in the country, the national weather service confirmed on Tuesday.

Most of the highs were recorded along the western Atlantic coast where temperatures have soared above 40 degrees Celsius (104 degrees Fahrenheit) and several forest fires are raging.

The all-time high temperature in mainland France dates to 2019 when the southern village of Verargues, north-east of Montpellier, clocked 46C.

Elsewhere, temperatures could locally exceed 40C in Belgium near the French border, prompting the Royal Meteorological Institute to issue its highest alert level.

In Germany, temperatures were expected to reach up to 40C in the west.

The hot, dry summer so far has raised fears of drought, with the German Farmers' Association president warning of "major losses" in food production./agencies