Travellers around the country have been encouraged to check the status of their flight before heading to the airport due to heavy rainfall shifting south towards Sydney.
Towns in parts of the New South Wales Mid North Coast have been smashed with half a metre of rain in just 72 hours, leading to the deaths of two men and a woman so far.
The SES has said more than 48,000 residents remain isolated due to rising floodwaters, as crews continue to conduct round the clock rescues via aircraft and boats.
That coastal trough is making its way toward the Harbour City, including the Lower Hunter, Central Coast, Blue Mountains and Southern Highland areas.
It is set to bring torrential rain, storms and further risk of flooding on Friday.
The Bureau of Meteorology has forecast much of NSW to receive 50 to 100mm of rain.
While those further west of the state can expect at least 25mm.
Due to the inclement weather, Sky News understands at least one airline had reached out to passengers travelling to Sydney to advise they check the status of their flight.
There appeared to be no issues with departures from Sydney on Thursday night.
The BoM said there will be showers for most of NSW on Friday.
“Storms with heavy falls possible along the coastal strip south of Sydney,” it said.
The Bureau also issued flood alerts for catchments across the Mid North Coast, with Macleay, Manning, Hastings, Paterson Rivers and Wollombi Brook at major level.
Water NSW has warned the Warragamba Dam may spill as early as Friday.
It is currently at 96 per cent capacity, but Water NSW stressed the potential spill could be delayed for days depending on the timing and location of the rainfall.
“The catchment area upstream of Warragamba Dam is over 9,000 square kilometres in area and inflows can be received from a number of different rivers,” it said.
“The Bureau is forecasting periods of intense rain overnight in the catchment, which could see the dam fill and begin spilling as early as tomorrow (Friday) morning under the Bureau’s less likely (25% chance) scenario.
“Under the more likely forecast (50% chance) scenario, the dam would begin to spill later Friday or into Saturday morning.”
Smaller dams such as the Nepean, Cataract and Woronora could experience small spills.
Residents in low-lying areas are encouraged to check the Bureau of Meteorology website for regular updates.
