Storms have soaked Sydney and NSW overnight, with 35mm of rain dumped in a hectic half-hour in some areas and giant hail crashing down in Newcastle.
The deluge began on Thursday evening and continued throughout the Harbour City's morning commute.
Southbound trains between Wyong and Gosford are suspended and major roads in Sydney are clogged.
The NSW State Emergency Service (SES) responded to about 250 emergency calls, mainly in the Hunter and metropolitan areas.
As wild weather lashed large parts of the state, golf-ball sized hailstones fell in and around Newcastle.
Chunks of ice with diameters of 5cm pelted Gresford, about 200km north of Sydney, about 4pm on Thursday.
About 34.2mm of rain fell in the Harbour City between 9:00am on Thursday and 8am this morning, with the showers expected to clear throughout the day.
On Thursday, parts of Queensland were also hammered by large storms.
Phil Campbell, from the NSW SES, said volunteers were bracing for a busy day, with more rain on the way.
"We've had some localised flash flooding and strong winds," he said.
"SES volunteers will be out this morning making temporary repairs to properties damaged in last night's storms."
