Anxious farmers counted the cost and sweltering workers breathed a sigh of relief Friday as a heatwave lifted from northern Europe after toppling decades-old temperature records.

At its peak on Thursday, the heatwave smashed national temperature records in Belgium, Germany and the Netherlands while Paris baked in its highest ever temperature of 42.6-degree Celsius (108.7-Fahrenheit).

But the mercury dived in France with outbreaks of drizzle as state weather service Meteo-France lifted "red" alerts imposed in 20 departments.

There was however no relief for some travellers seeking to make their holiday getaways, with severe railway delays in Britain and France in the aftermath of the extreme heat.

This picture taken on July 25, 2019 shows a thermometer indicating a temperature of over 40 degrees at a Royal Netherlands Meteorological Institute (KNMI) weather station at the Deelen Air Base in Arnhem, the Netherlands. AFP

- 'Heat burst' -

The county of Lincolnshire in eastern England saw a hugely-unusual "heat burst" Thursday evening, with temperatures soaring from 22C to 32C and then back down again to 22C over the course of an hour.

"This was due to a thunderstorm collapsing and bringing hot air from aloft down to the surface," the Met Office weather service tweeted.

In Germany, the country's highest mountain the Zugspitze -- standing at 2,962 metres (9,718 feet) -- was still almost completely covered in snow despite a national temperature record of 42.6 degrees Celsius (108.7 Fahrenheit) Thursday in the north.

"The thick snow cover has provided a buffer against (the mountain) absorbing the high temperatures this year," a spokesperson for the research station at Zugspitze said.

Finland's Meteorological Institute warned the thermometer could exceed 35 degrees Celsius (95 Fahrenheit), breaking this summer's high of 32.3C (90.1F).

While some Finns tried to escape the heat, others were not deterred from swimming in lakes and the sea, despite an outbreak of poisonous blue-green algae in popular spots.

In Paris, with public swimming pools overcrowded, many locals and tourists sought to cool off in public water features, notably the giant fountains at the Trocadero close to the Eiffel Tower.

"It is too hot to stay in the city in the daytime, there is nothing to freshen with. So for the kids it's very cool to have this place with water," said Norwegian tourist Yensi.

A woman wades through water with her horse to refresh him in a lake in Lamotte-Beuvron, south of Paris, central France on July 25, 2019 AFP

- Flights cancelled -

Commuters and holidaymakers saw travel plans blighted with disruption to air and rail services in several European countries.

Flights at London's Heathrow and Gatwick airports were cancelled and delayed -- some by over two hours -- with holiday destinations such as Alicante, Rome and Lisbon affected.

Elsewhere in the British capital there was still travel havoc due to rails buckling under the heat and fires breaking out along commuter lines. The Met Office advised against non-essential travel.

At Paris's Gare du Nord, an electrical failure halted domestic and international high-speed trains Friday lunchtime, including Eurostar and Thalys services although traffic gradually resumed.

Thalys -- which links Paris to Brussels, Amsterdam and Cologne -- also saw disruption with slow trains amid fears infrastructure could overheat.

At the peak of the heatwave, temperatures on the tracks soared to up to 15 degrees Celsius (59 Fahrenheit) higher than that of the air.

In Switzerland, train engineers painted rails white to reflect the heat of the sun.

A man sprays water to refresh a horse in Lamotte-Beuvron, south of Paris, central France on July 25, 2019, as a new heatwave hits western Europe AFP

- 'Catastrophic heat' -

The heatwave has been particularly brutal in the countryside, aggravating fires which have seen thousands of hectares of crops destroyed in northern and central France.

"More than 3,200 hectares have already gone up in flames since the start of summer," Interior Minister Christophe Castaner said.

French Agriculture Minister Didier Guillaume said Thursday that farmers in worst-affected areas would receive additional Europe-backed funding and the right to graze their animals on land not normally used for agriculture.

"It's catastrophic in terms of heat, so we're hoping the weather gets back to normal so that we can have a few flowers," said Jason Augusto, a beekeeper in the Sologne region of northern France.

Air base personnel look at an instrument of the Royal Netherlands Meteorological Institute (KNMI) weather station at the Deelen Air Base in Arnhem, the Netherlands, on July 25, 2019 AFP

A picture shows corn fields scorched by the hot weather and lack of water on July 23, 2019, in Longue-Jumelles, north western France AFP

Engineers test rails painted in white to lower the temperature during a press conference by the Swiss Federal Railways on July 26, 2019 in Zuchwil near Solothurn AFP

A picture taken on July 23, 2019 shows a lettuce growing in a field at the "Rosée des Champs" cooperative in the Val d'Authion, as a new heatwave envelopes western Europe AFP

Holidaymakers are seen on the South Beach,Tenby, Pembrokeshire, Wales, Britain. July 25, 2019. REUTERS