More than 50 flights departing from Sydney airport have been cancelled as bad weather grounds aircraft.
Two of the three runways at the airport are expected to close shortly, leaving all domestic and international flights to share a single runway.
Airservices Australia says the imminent closure is due to safety concerns about heavy rain and wind in NSW.
"Sydney Airport is expected to shortly move to operating off a single runway due to poor weather conditions," a spokesperson said.
"Safety is our number-one priority."
Forty-nine domestic flights and two international flights have been terminated as a result.
The cancellations come amid warnings from Sydney Airport that the upcoming school holiday period is expected to be even busier than the last.
The spike in air travel has coincided with the National Day of Mourning public holiday and Sydneysiders travelling to Melbourne for the AFL grand final on Saturday.
Sydney Airport chief executive Geoff Culbert says he expects nearly 2.4 million passengers to pass through the airport over the next three weeks.
"The school holidays will test us again, and we are expecting the terminals to be busy during peak periods, especially Thursday, Friday and Monday mornings," Mr Culbert said.
"Passengers should continue to arrive 2 hours prior to departure for domestic flights, and three hours ahead for international."
Mr Culbert says the airport is better-placed than at any time during the post-COVID period to handle the spike in demand.
But labour shortages continue to cause problems, with thousands of roles remaining vacant across the airport.
Sydney's domestic terminals have faced months of delays and overcrowding as the airport struggles to adjust to normal travel levels.
In August, total passenger traffic at the airport returned to 72.5 per cent of pre-COVID levels.
Passenger queues have extended out of the door several times since April, with many travellers waiting outside for hours just to check their baggage in.
On Wednesday, Sydney Airport hosted a jobs fair to try and fill the labour shortage that was created after a large portion of the workforce was let go during lockdown.
"All of the organisations across the airport have been working hard to rebuild their workforces and we are seeing improved operational performance on most days," Mr Culbert said.
"But labour shortages are an ongoing challenge with around 4,000 open roles across the airport."
Sydney Airport says passengers who are unsure whether their flight has been cancelled should contact their airline directly.
