The Bureau of Meteorology has issued a severe weather warning for heavy rain that may cause flash flooding with the heaviest falls expected to hit the Illawarra, Hunter, Central Coast and Greater Sydney from Saturday evening into Sunday.
Wollongong in the Illawarra, the eastern suburbs of Sydney and up to Newcastle in the Hunter could get up to 100mm while other areas will have between 30mm and 50mm.
Most areas will not experience a sudden downpour with the rainfall totals to accumulate over the next 48 hours.
"So even if it's only taking up eight or 10mm an hour, if we did that for several hours in a row, that's still a lot of rainfall by the time of day," senior meteorologist Angus Hines told AAP.
Mr Hines warned the rainfall may lead to flooding as the east coast is already saturated after a dumping in April.
"This is significant rainfall that could lead to flooding, perhaps localised flooding, certainly blocking terrain, closed roads and traffic jams," he said.
The deluge is far less than a month ago when floodwater reached the top of cars in some areas of the Illawarra and Sydney.
"So we're not expecting to see the same type of flood response, but it's enough rain that we will probably see some areas of localised flooding and Illawarra is again in the firing line," Mr Hines said.
⚠�🌧�Severe Weather — Bureau of Meteorology, New South Wales (@BOM_NSW) #Warning issued for heavy rainfall that may cause flash flooding in the Illawarra District overnight and during Sunday, including Wollongong, Bulli, Port Kembla, Albion Park, and Kiama. Details and updates: https://t.co/Ss766eSCrL pic.twitter.com/ONuhWm5WHhMay 4, 2024
Thunderstorms are also possible inland north of Griffith, and along the east coast around and north of Wollongong on Saturday.Â
A hazardous surf warning continues from the Illawarra Coast to the Byron Coast, contracting to the Byron Coast on Sunday.
Despite the wet predictions, the Sydney Half Marathon is set to go ahead on Sunday with more than 19,500 runners registered.Â
The NSW State Emergency Service is closely monitoring forecasts with all flood rescue personnel rostered on for any potential issues.
SES Zone Commander Allison Flaxman said the agency is focusing on flash flooding where roads could be cut off.
"We don't need much rain to cause a flash flood scenario ... it only takes 15 centimetres of water across a road to actually move a car," she said.
The worst of the rain is expected to hit on Sunday and into Monday morning with falls peppering the east coast through next week.
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