As of this week, autumn has officially begun and the leaves have started to fall. For those in Portugal, however, temperatures are still sky-high. 

Holidaymakers heading to the popular destination have been caught in a scorching heatwave this week, with temperatures reaching up to 40C (104F) in some spots. 

Over in Lisbon, where many may have intended to enjoy cosy trips to cafes and bars, visitors were hit with highs of 36C (97F), Euronews tells. 

In fact, the Portuguese Institute for Sea and Atmosphere (IPMA) weather service even issued heat warnings for some parts of the country.

Authorities are also reported to have warned locals of the risk of forest fires in inland areas. 

For today, September 25, there are yellow and amber high temperature warnings in place for the Madeira Islands. 

IPMA forecasts 36C (97F) for the city of Evora, 35C (95F) in Castelo Branco and 31C (88F) in Lisbon. 

Meanwhile, over the weekend temperatures are set to continue to remain high before beginning to drop slightly.

'I wasn't expecting this heat,' Canadian tourist Shamminaz Polen told Euronews.

'In fact, I even brought a coat because I thought it would be cooler and similar to Canadian autumn weather, around 21, 23 degrees Celsius, and I told my friend the same thing: 'Bring a coat'.'

British tourist Fletcher Shepard, who visited Lisbon, said: 'It's very dry, obviously it's quite pleasant here in the shade and in the shops and so on, but when you're walking in the sun it can get really very hot.'

The fresh heatwave comes after a summer of red-hot temperatures across Europe. 

In the UK, Britons experienced the hottest summer on record. The highest temperature was 38.2C, in Gloucestershire, the BBC reports. 

Elsewhere, destinations such as France and Spain were hit with devastating wild fires.

Several Greek islands also faced water shortages and declared a state of emergency as reservoirs dried up.

River cruises across Europe have also been affected by the heat.

The Danube has hit record-low levels of water, while a cruise ship carrying holidaymakers ran aground in Bulgaria in July and had to be evacuated.

A Second World War-era Nazi ship even emerged from the waters in Serbia.

Meanwhile, the Rhine fell to dangerously low levels, leaving cargo vessels stranded and raising fresh concerns for cruise operators.

Major cruise companies were even forced to rethink their summer itineraries, with some sailings cancelled altogether.