Rainfall is set to lash NSW, Victoria, the ACT and southern Queensland while the Tropical North goes through heatwave conditions this week, according to the Bureau of Meteorology.
Sydney, northern NSW and southern Queensland were lashed with rain over the weekend.
In NSW, Port Macquarie copped 54mm of rain in the last 24 hours while Brisbane received 22mm and parts of Sydney received 16mm in the last 24 hours.
BoM meteorologist Jackson Browne said this wet weather was expected to continue in the coming days in his weekly weather update.
"On Monday, the low in the east stalls over northeast NSW and southeast Queensland, weakening in place. The system in the west moves into the Bight, dragging down tropical moisture from storms near Java," Mr Browne said.
"On Tuesday, the low and associated trough strengthens and fires up widespread thunderstorm activity over inland WA, NT and SA. A high in the Tasman begins pouring moisture once again into eastern Australia, increasing rainfall. Another high moves into the Bight, settling conditions to the west of the trough.
"Wednesday, the now-deep low-pressure system and trough combines both moisture streams over eastern Australia, signalling widespread rain and storms across multiple states. This rainfall will persist while slowly translating towards the coast on Thursday and Friday."
Mr Browne said a high-pressure system would push moisture north on the weekend, which would keep the south of the continent relatively fine.
IN OTHER NEWS:
Meanwhile in the tropical north, there would be heatwave conditions in cities such as Darwin, Cairns, Broome and Townsville this week.
"Heatwave conditions persist in the tropical north stretching in an arc from Broome to Townsville," Mr Browne said.
"A succession of unusually hot days and very warm nights coupled with humid conditions will place a large amount of thermal stress on people livestock and infrastructure. This is in excess of typical conditions."