More than 35,000 people are expected to attend what is now effectively the farewell show today.
The air show has been under threat since the announcement that Leuchars was to close as an RAF base.
The RAF said it was "giving serious consideration" to various options, including a replacement, but did not give any guarantees the event would be held in Scotland.
Making the announcement only hours before the show opened that this year's event would mark the end of an era, Dr Andrew Murrison, defence minister responsible for Scotland, said RAF personnel at Leuchars were to be congratulated for staging such "wonderful" shows.
"Since the first Battle of Britain at Home day event held there in 1946, the station has thrilled hundreds of thousands of people with its air-power displays and I am delighted the RAF will continue to support public events in Scotland in 2014 and beyond."
Stirling will be the host city for Armed Forces Day next year while there will be military participation at the Commonwealth Games.
SNP Westminster defence spokesman Angus Robertson said the farewell show was a reminder of Coalition cuts.
"It is incredibly sad that this will be the last show at Leuchars, and it has not been confirmed if the air show will take place elsewhere, and if it will stay in Scotland.
"The fact this is the last air show to take place in Leuchars is another reminder of the UK Government cuts our armed forces have faced.
"The UK Government had the opportunity to reverse more than a decade of decline in Scotland's military footprint but instead made further massive and disproportionate cuts to the RAF and Royal Marines, as well as the closure of military facilities."
Air Officer Scotland and Station Commander RAF Leuchars, Air Commodore Gerry Mayhew said that the reality was that after the 2013 air show the RAF would be "fully committed" to relocating to Lossiemouth.
He said: "The Typhoon squadrons based here at RAF Leuchars and their Quick Reaction Alert mission will move to RAF Lossiemouth over the course of the summer and into the autumn of next year, so it is impractical for the Royal Air Force to host an air show here next year."
A 93-year-old RAF veteran who was awarded the Victoria Cross returned to the skies yesterday in a replica of the aircraft he flew during the Second World War.
John Cruickshank, from Aberdeen, is the only RAF veteran living in Scotland to have the highest military honour for valour in the face of the enemy.
He was welcomed to RAF Leuchars in Fife by station commander Air Commodore Mayhew ahead of Scotland's largest airshow.
The veteran boarded the Catalina flying boat, one of the aircraft which will feature in the Leuchars Airshow.
The crew took Mr Cruickshank on a 20-minute round trip flight to Dundee.
On July 17, 1944, on his 48th mission, Flying Officer Cruickshank was captain and pilot of a Catalina flying boat that sunk an enemy submarine close to the Arctic Circle.
One crew member was killed in the attack and Mr Cruickshank received 72 injuries.