People munching breakfast on the Sydney Harbour Bridge when it shuts down on Sunday morning have been urged to bring a raincoat but not their car.
Some 6,000 ticket holders drawn from a ballot will be able to enjoy a picnic on the world-famous span for two hours from 6.30am (AEDT), when it temporarily closes to traffic.
The inaugural Breakfast on the Bridge is the marquee event for Crave Sydney, a month-long festival showcasing the city's entertainment, food and art.
Tourism Minister Jodi McKay has promised a blockbuster "once-in-a-lifetime" event which will attract world-wide attention and highlight Sydney as a unique destination.
"We don't do events by half," she told reporters on Thursday.
"This is a massive event, but we want to be bold, we want to be brave in terms of hosting these events because that's what you expect from a global city like Sydney."
The bridge will be closed for 12 hours from 1am on Sunday while preparations are made, including about three hours to lay 10,600 square metres of grass which will transform the tarmac surface into a giant green park.
Weather forecasts are unfavourable, but Ms McKay has assured ticket holders the event will go ahead rain, hail or shine, reminding people they'll need more than just their breakfast.
"Come prepared for rain ... we don't want umbrellas on the bridge, but they need to bring a poncho or raincoat," she said.
"We do believe that the weather won't be kind to us but it is going to go ahead rain, hail or sunshine, and we have certainly got the precautions in place if it does rain."
The event will showcase regional produce by offering free fruit, bread and yoghurt.
It will coincide with the Seven Bridges Walk, inviting Sydneysiders to take in the sights of the harbour and surrounds, among a series of other Crave events.
Traffic changes will be put in place and extra public transport will be operating throughout the day.
NSW Transport and Infrastructure says clearways will be enforced, allowing motorists to easily bypass the city, while the Sydney Harbour Tunnel will remain open.
Extra train shuttle services will run between Central Station and North Sydney and more buses will be on the roads.
"We can all enjoy this event at the weekend if Sydney people do what they always do and leave the car at home," Les Wielinga, of Transport and Infrastructure, said.
"There will be a strong and very robust public transport system in place. Please come and enjoy the event, please come and leave the vehicle at home."