Weather events and natural disasters unfolding across popular European travel hotspots are triggering travel chaos for tourists.

On top of a record-breaking heatwave baking the continent and sparking warnings for France, Spain and Portugal, large parts of Europe are dealing with wildfires and the effects of a volcanic eruption in Italy.

Hundreds of firefighters are battling blazes that have devastated more than 19,000 hectares (42,000 acres) of land - an area more than twice the size of Manhattan - across Portugal, Spain, France and Greece. 

Meanwhile noxious clouds swept through Greece and Costa Brava in Spain was put on alert.

Major fires also destroyed hundreds of hectares of forest, vineyards and scrubland on the Croatian island of Hvar and at Tale in Albania, authorities said. 

Airports remain open, with the exception of Catania in Italy, but travellers are warned to expect flight delays or cancellations due to airspace bottlenecks and heatwave conditions, with more than 3,000 delays in a single day recently reported.

Italy 

Mount Etna erupted again for the ninth straight day, following the beginning of activity last week.

The volcano, located on the east coast of Sicily, ejected a huge cloud of volcanic ash on Sunday morning, local time.

Authorities have triggered a red alert for the area, disrupting flights at Catania Airport.

The airport is the main transport hub for eastern Sicily, a tourist hotspot.

Incoming flights were suspended due to safety concerns while the path of the ash cloud was assessed. 

Italy's national carrier ITA has since cancelled flights to and from Catania until 2pm on Monday, local time.

It's understood several planes were diverted to Palermo, in northern Sicily.

Those with affected flights have been urged to contact their airline.

Portugal 

In Portugal, emergency services said they had controlled '80 per cent' of a wildfire that has devastated some 13,000 hectares of forest and scrubland in the north of the country.

Already one of the warmest countries in Europe, authorities on Monday issued heatwave alerts at the highest 'red' level for the districts of Portalegre, Évora, Beja, Santarém, Lisbon, Setúbal, Castelo Branco, Guarda, and Bragança.

Spain 

In Spain, a fire near the northeastern Costa Brava coast burned more than 2,200 hectares in two days and firefighters said their efforts would be 'complicated' by rising temperatures and the many 'smoking hotspots' within the fire's perimeter.

Almost 50,000 people living nearby were ordered to remain indoors or were evacuated, according to local media.

A man was detained on suspicion of accidentally starting the blaze while using an angle grinder for roadside work.

France

In southwestern France, near the city of Perpignan, 700 firefighters backed by special aircraft battled to control a 'gigantic' blaze spreading in a hard-to-reach remote area, with more than 10,000 local residents evacuated.

Fanned by wind, intense heat and exceptionally dry air, the fire has nearly tripled in size since early Sunday, devouring 4,600 hectares and leaving a firefighter and a resident injured, local authorities said.

'The fire came within 300 metres of the houses. We were taken aback by how fast it spread, it was staggering - bordering on panic,' said Patrice, a 53-year-old resident of the village of Trevillach.

'We started seeing smoke around 10.30pm, then it kept coming closer and closer. Someone from the town hall knocked on our door around 1.00am to tell us to leave,' said Charlotte Pignol, 30, who was among the first to be evacuated from her home early on Sunday.

The blazes come shortly after a heatwave in June, one of Europe's worst, during which thousands of excess deaths were registered and which would have been 'virtually impossible' without climate change, the World Weather Attribution group of scientists said.

With the mercury set to rise again in the coming days, authorities expressed alarm that the annual summer wildfire season had started a month early.

'Climate change is here, we are living the consequences and it is only the start of July,' said French fire service Colonel Eric Belgioino as he appealed to people near the Pyrenees inferno to take precautions to avoid starting fires.

'The season is going to be long for the soldiers fighting fires. You have to help us,' he pleaded.

Officials announced that Monday's third stage of the Tour de France cycling race through the Pyrenees would take place without spectators who normally line the routes of the storied competition.

The stage, which on Monday will see cyclists ride from Spain into France, 'will be limited to the passage of the riders only and the vehicles essential to organising the race' on French territory, the regional prefect Pierre Regnault de la Mothe told reporters.

'The public is asked not to go near the route or to the finish area,' he said.

'In other words, and I regret having to say this, it will be, in France at least, a stage of the Tour de France without spectators.'

Greece

In Greece, flames set off by a forest fire tore through two factories in Thessaloniki in the north of the country over the weekend, forcing authorities to evacuate the surrounding area and to warn households to keep their windows closed.

Evacuation alerts were activated for three suburbs as well as a facility housing 157 people with special needs. 

The blaze started at a recycling plant near the Oraiokastro suburb on Saturday evening.

Ferocious winds fanned the flames and around 160 firefighters were deployed to battle the inferno through the night until water-dropping aircraft could take off at dawn.

A 76-year-old man was arrested on suspicion of having started the fire through negligence by generating sparks with his vehicle that set vegetation near the road alight, according to the fire department. 

Brig. Ioannis Artopoios, fire department spokesperson, said 85 per cent of wildfires in Greece are caused by negligence, including through sparks generated through the use of agriculture machinery, discarded cigarettes and the use of outdoor barbecues. 

'This means most of them could have been avoided,' he said.