A looming low pressure system is set to intensify, bringing possible flooding to parts of eastern Australia as residents are told to expect a "potentially severe" couple of days.
The Bureau of Meteorology has issued warnings for totals which could exceed 200mm in parts of eastern NSW including Sydney on Tuesday and Wednesday.
Wild and hazardous surf conditions are also on the cards.
Senior bureau forecaster Angus Hines said persistent rainfall in the region could result in flooding and eastern rivers rising.
"We also anticipate strong or damaging wind gusts across much of eastern NSW again," he told the ABC on Saturday.
Dangerous conditions are forecast for coastal waters that could lead to inundation or erosion, Mr Hines said.
"So a really active, busy, potentially severe couple of days and then it should all wind down on Thursday," he said.
Low pressure systems drag air inwards and pull it upwards, with the air cooling and forming clouds.
An east coast low is a low pressure system that meets a few other criteria, including how intense the low pressure gets, how long it stays near the country and how severe the weather impacts associated with that weather system become, Mr Hines said.
Meteorologists will continue to monitor the system over the weekend with rain expected to ramp up on Monday.
"I can't say for certain whether this is shaping up to be an East Coast low but ...it is still going to be a significant weather system," Mr Hines said.
"It is still going to bring some pretty powerful weather impacts to eastern New South Wales, including likely around Sydney through the middle half of next week."
Residents in affected areas are told to keep up to date with the Bureau's warnings and forecasts.
