The great summer getaway has begun with millions packing up the car and taking to the skies, with roads and airports set to be heaving.
As the school holidays begin and the weather forecast unseasonably bad, many will be glad to relocate to sunnier climes.
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.
"The strong pound to euro exchange rate also means that holidaymakers' money will go much further in eurozone resorts," he said.
With many airports predicting record numbers this weekend, holidaymakers should leave plenty of time to get to the airport as the roads will be "extremely busy" and those travelling by public transport should check for any potential engineering work, the spokesman added.
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.
Preparation and planning for big peaks in demand begins months in advance with NATS analysing airline schedules and airport capacity, and the plan is constantly tweaked and updated.
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."
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.
"The terminals will be staffed with extra volunteers and passenger ambassadors to advise on everything from check-in, to what gate to go to, how to entertain the kids whilst waiting for the flight, or what restaurant to eat at," she said.
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.
Roads are expected to be busy too, with RAC spokesman Simon Williams 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."
Heathrow Airport said the previous busiest day for departures was May 22 when there were 129,000 departing passengers.