The great summer getaway could be marred for millions by bad weather, "road misery" and industrial action.
As the school holidays begin, Britons will be packing up the car and taking to the skies, with roads and airports set to be heaving.
But it could be less of a jolly holiday and more of a travel nightmare due to "intense" rain and wind battering parts of the UK, a strike planned by Spanish Air Traffic Control services over the weekend, and a 5.0-magnitude earthquake near Greek islands earlier today.
The quake hit near the holiday island of Kos, but authorities say there were no immediate reports of any injury or serious damage.
Meanwhile in France, angry farmers finally relented after a day of protesting against low milk and meat prices by blocking roads to Mont Saint-Michel and the Alps, but they warned that more action is on the horizon.
Air traffic controllers at NATS said it is likely to be the busiest day of the year, while Heathrow Airport is expecting its ''busiest day ever'' with an extra 31,000 passengers taking off.
Travel association Abta estimates that 2.1 million holidaymakers will head overseas, and a spokesman said the wet weather might tempt more people to make a last-minute booking.
"With rain predicted for many parts of the UK late bookers may also be tempted to head off overseas with temperatures around the Mediterranean set to hit the mid to high 30s over the next few days with guaranteed sunshine," he said.
MeteoGroup weather forecaster Billy Payne said it is ''unusual'' to see so much rainfall in 24 hours.
''We are looking at some very heavy rain across much of southern Britain today and into tonight," he said, adding: ''It's quite intense.''
RAC spokesman Simon Williams is predicting "road misery" and calling for drivers to stay calm.
"The combination of the remaining schools breaking up, the biggest flying day of the year and a typical British summer's rainy day is a recipe for road misery today as around two million cars bound for holiday take on normal commuter and business traffic.
"The heavy and persistent rain will make driving conditions challenging and there is a real risk that delays may lead to frustration behind the wheel.
"It is important all drivers, but particularly those desperate to get to their summer destinations, keep their cool so that their well-earned breaks don't begin with an accident.
"On Saturday in excess of two million motorists will be setting off on their summer holidays. In order to avoid the inevitable jams on routes to the coast, such as the M5 to Devon and Cornwall, drivers should set off as early as they possibly can."
NATS has been preparing for weeks to ensure flights get away safely and with the minimum of delay, adding that routes to all the usual holiday destinations in Spain, the Canaries and southern Europe are expected to be busy.
Juliet Kennedy, operations director at NATS' Swanwick Control Centre in Hampshire, said: "We have been working incredibly closely with our airline and airport partners to make sure the whole system is prepared and ready to handle today's influx of passengers and flights.
"We want to make sure everyone can get away for their well-earned break easily, efficiently and safely."
On its website, easyjet refers to the Spanish Air Traffic Control strike in its latest travel information section.
"We have been advised of planned industrial action by Spanish Air Traffic Control services on Saturday 25 July and Sunday 26 July.
"We plan to operate our normal schedule and like all airlines flying to and from Spain, we expect to be impacted by moderate delays during this period as a result of the strike.
"We recommend that all customers flying to or from Spain on those dates check the status of their flight on our Flight Tracker page before going to the airport," the airline said.
NATS said they are expecting the Spanish strike to have "minimal impact" on UK operations, adding that passengers should contact their airline for information about their flights.
Meanwhile, in France yesterday farmers used tyres, tractors and tree trunks to block roads across the country - a day before many French people will also take to the roads to start their summer holidays.
Mont Saint-Michel, in Normandy, is a Unesco World Heritage Site and tourists were forced to park their cars along the road and walk for several miles to the famous island.
The farmers also blocked three major roads for eight hours around the eastern city of Lyon, a gateway to the Alps and the south of France. Traffic had backed up 15 miles by midday.
Some roads in western France, a region with many milk and pork farms, were also jammed.
Farmers say their profits are being chipped away by cheap imports and pressure from shops. Low prices have put about 10% of France's livestock farms on the verge of bankruptcy, according to the government.
Xavier Beulin, president of FNSEA, the main farmers' union, warned of further possible protests ''in the next two to three days''.
And the protesting farmers, migrant crisis in Calais, and wildcat strike action by ferry workers mean truckers are spending hours stuck in queues in Kent and northern France.
Further delays hit cross-Channel services when the body of a suspected migrant was found on the roof of a Eurotunnel train at the Chunnel terminal in Folkestone yesterday.
Operation Stack - where freight traffic is queued on sections of the M20 when cross-Channel services are disrupted - remains in place, and Kent Police warned it could continue until at least Sunday.
A Heathrow spokeswoman said that on a "normal" day the airport has an average of 200,000 passengers going through - with arrivals and departures roughly divided 50:50.
Today they will have an extra 31,000 passenger departing and by 8.30am almost 29,000 passengers had gone through security, she said.
It is set to be "the busiest day ever" with 131,046 passengers flying out of the airport.
Heathrow Airport said the previous busiest day for departures was May 22 when there were 129,000 departing passengers.
Spain remains the number one destination for the UK market and, with the pound at an eight-year high against the euro, holidaymakers are flocking to other eurozone countries including Cyprus, France and Greece. Florida remains the number one long-haul choice for families, according to Abta.
British Airways said it plans every year far in advance for the busy summer period, adding that it is "working hard" to help customers get away.
Short-haul destinations popular with BA customers include Rome, Barcelona and Edinburgh, while the top long-haul places include New York, Boston and Hong Kong.