There may, weather permitting, be a chance to see up to 35 hot air balloons drifting gracefully across the London skyline on Sunday morning.

If the weather permits — and the current outlook is favourable — then they will take off from London City Airport around 7am on Sunday.

UPDATED 3pm Sat – The launch has been confirmed with an expected track heading towards Dagenham, Hornchurch, Upminster, Brentwood, and Billericoy.

It is the first time the regatta has launched from London City Airport, this year forming part of the airport’s 30th birthday celebrations. The regatta was originally scheduled for June but was re-scheduled due to unfavourable weather conditions.

Balloon pilots from the UK, France, Spain, Belgium and the USA will form an international line-up of balloons, including London City Airport’s own newly commissioned 30th birthday hot air balloon.

When the launch happens, during the 15-minute launch period, London City Airport is likely to be one of the busiest international airports in the world, based on the number of ‘movements’.

According to air traffic alerts, the balloons can be expected to head southwards from London City Airport for up to 17 miles – which is pretty much out to the M25 boundary.

Viewing of the lift-off may be best from the north side near Royal Albert DLR, as the airport itself will be closed, to both planes and people. London City Airport will stream the regatta live on its Facebook page but there will be no official spectator facilities at the airport.

The balloons will remain airborne for approximately one hour, with winds likely to take the group in a north-east direction before they disperse and land.

The Lord Mayor’s Regatta will post an update tomorrow afternoon to confirm if the balloon lift-off will take place.

If it doesn’t they have stand-by dates for 24th Sept and 1st Oct.

The regatta, now in its third year is designed to raise awareness of and funds for the Lord Mayor’s Appeal.

(updated: Fri 8pm to change the expected direction of the flight from south to north-east)