Holidaymakers across Europe face sweltering temperatures as a “dangerous” heatwave hits the continent.
Scorching temperatures are forecast for countries such as Spain, Italy and Croatia with the mercury set to hit 40C prompting severe warnings.
Tourists planning to escape the burning heat could also face severe delays, with people flying home this weekend being urged to arrive at airports at least three hours before their flight due to new passport controls.
Queues of up to four hours have been reported since the introduction of more stringent checks on travellers entering and leaving the Schengen area, which allows passport-free movement across much of the EU.
Airports in Spain, Portugal, France, Italy and Belgium have been affected with some travellers receiving texts to notify them of the delays.
The situation could worsen this weekend as lobby group Airlines For Europe (A4E) warned it will be one of the busiest of the year with 10 million people expected to pass through European airports on Saturday and Sunday combined.
Some countries such as Majorca are predicted to experience double their usual demand.
British Airways, easyJet and Ryanair have all alerted passengers to the need to turn up at airports earlier than normal.
BA is sending text messages to passengers flying back from airports where long lines at border controls are expected.
A spokeswoman said: “We’re texting customers flying from airports that we know are having issues to ask them to arrive early.”
The carrier has promised that any customers who miss their flight because of the queues will be re-booked for free.
EasyJet told passengers it strongly recommended they allow extra time at airports “to be able to get to the gate on time”.
The security measures were brought in following terror attacks in Paris and Brussels.
They have led to long lines at border controls as the details of passengers from non-Schengen countries – such as the UK – are run through databases to alert authorities if they are known to pose a threat.
As travel chaos looms, Italians have dubbed the heatwave Lucifer with 11 countries braced for “dangerous” weather conditions which include Serbia, Hungary, Romania, Croatia and Poland.
Warnings were issued for 26 European cities as a heatwave from Africa starts to sweep the Mediterranean with high temperatures expected until at least Monday.
A “red alarm”, indicating the highest level of risk from the heat, has been issued for popular Italian cities Florence, Rome, Venice and Verona.
In the capital, tourists taking in city sights under the scorching sun could be seen making good use of Rome’s many water fountains, re-filling their bottles and pouring water over their heads. Meteorologists forecast temperatures of around 40C for Rome and several parts of Italy until Monday.
In the south and Sardinia, temperatures are expected to reach highs of 42C.
Highs of 43C are set to hit parts of Spain this week with the most intense heat expected in Granada, Seville and the Costa del Sol over the coming days.
Tourists have been advised to stay in shaded areas while warnings are in place.
The fresh alert was issued after an earlier heatwave caused severe forest fires on the Spanish southern coast.