While Britain welcomes Olympics arrivals, around two million people will be heading abroad at the start of the school holidays this weekend.
And for those taking breaks in the UK, there was a promise of better weather, with conditions expected to be warmer, drier and sunnier.
The AA warned that major road routes were likely to be busy from mid-afternoon today.
Travel organisation Abta said that for those travelling overseas, Spain and its islands were the number one destination followed by Turkey and Greece.
Those choosing a foreign trip are being boosted by a marked improvement in the number of euros they will get to the pound.
Abta added that prices in restaurants and bars in Europe were falling.
Over this weekend, around 482,000 passengers will leave from Heathrow, 275,000 from Gatwick, 132,500 from Stansted and 70,000 from Luton this weekend.
More than 100,000 will fly from Scottish airports, including 50,000 from Glasgow.
It is expected that 297,000 will leave from Manchester, 64,000 from Birmingham and 45,000 from Bristol.
About 50,000 will depart on Channel Tunnel high-speed Eurostar trains, while regional airports, ferry terminals and Eurotunnel's Channel Tunnel services will all be extremely busy.
Abta chief executive Mark Tanzer said: "This weekend marks the start of the summer holiday getaway and is expected to be one of the busiest of the year at UK airports, with thousands also arriving for the Olympics.
"Eurozone destinations are proving popular with holidaymakers looking to take advantage of the pound's strengthening against the euro, coupled with the fact that many bars and restaurants have lowered their prices."
Those staying at home who have had to endure one of the UK's coldest, wettest and dullest summers ever, can at least look forward to something better.
Forecasters predicted that although it could be wet today and showery tomorrow conditions, at least in southern England, will improve considerably on Sunday and Monday, with temperatures as high as 27C (81F).
AA Roadwatch and traffic information company Trafficmaster said routes to the south west of England were likely to be the busiest today, while congestion could also be expected on main routes to the coast, cross-Channel ports and major airports.
Among the routes likely to see the worst jams are the A303 through Hampshire, Wiltshire and Somerset and the M6 through Staffordshire and Cheshire into Lancashire.
Next week Trafficmaster expects that regular commuter traffic will be substantially reduced but traffic around Greater London will be increasingly affected by the final preparations for the Olympics.
The Olympic travel-only Games Lanes will become fully operational from Wednesday in central London.
An AA/Populus survey of more than 20,000 AA members showed that around a quarter will not drive as far for their main holiday this year compared to last, with Londoners, Scots and those in north west England the most likely to cut back on mileage.
Around a fifth (19%) say they will drive further this year, particularly the Northern Irish (22%).
As many as 27% said they would spend more on their main holiday this year, with 25% spending less.
Londoners are the most likely to head overseas, while the Welsh are the ones most likely to do without a holiday.
A poll of 2,000 motorists by car insurance company Admiral showed that one in seven felt agitated ahead of their summer holiday road trips, with congestion topping the list of concerns.
As many as 18% said they did not plan their route.
Also, a survey of 2,001 people by Kwik Fit showed that only around two in five families play traditional in-car games on long journeys, with most now passing the time with headphones on, listening to iPods and other electronic devices.
Another survey - of 3,000 people by car company Nissan - revealed that 20% of towers of caravans, trailers or boats have only taken up the pastime in the last six months.
Also, 40% of the towers admitted they had never had training on how to do it safely.