A significant flood warning has been issued across regions from the NSW coast to inland suburbs due to forecasted heavy and prolonged rainfall, with some areas expecting over 125mm in a 24-hour period, which could lead to minor to moderate flooding and major river rises.

In May, flooding in Taree caused destruction and fatalities, with the Manning River reaching nearly 6.5 meters, illustrating the potential severity of current conditions.

Severe weather warnings have been issued for southwestern Western Australia, including Perth and surrounding areas, due to expected heavy rain and damaging winds, with Perth experiencing 53mm of rain in 22 hours.

Western Australia's west coast faces heavy rain, damaging winds, and flash flooding risks from a cold front and moisture from the Indian Ocean, with wind gusts reaching 111 km/h at Cape Leeuwin.

The rainfall is expected to cause rising river levels, especially impacting the Peel and Namoi rivers, with flood watches extended to 15 rivers across NSW, including the Macdonald River near Sydney.

Recent heavy rains have saturated the land, with parts of the east coast, including Sydney, receiving three to four times their usual August rainfall, totaling 250-300mm since August 1, worsening flood risks.

The Bureau of Meteorology warns that the main threat is the prolonged duration of rain, which could cause flooding even if hourly rainfall remains moderate, with the worst conditions expected on Thursday after 24 hours of continuous rain.

Overnight, significant rainfall was recorded along the NSW coast, with totals such as 82.4mm at Point Perpendicular and 74mm at Parrearra, and this rainfall is expected to ease from Friday.

Meteorologist Helen Reid highlighted that the cumulative effect of moderate rainfall over several days could lead to large total rainfall amounts by the weekend, increasing flood risks.

Authorities are warning residents against driving through flooded roads, advising to turn around if they encounter such conditions to prevent accidents.

NSW SES is preparing for an increase in emergency calls by deploying aircraft, vehicles, and crews, and residents are urged to stay informed via the Hazards Near Me app.

This week has also seen some of the coldest nights of the year across Australia, with Thredbo recording -13.2°C, the coldest temperature since 2018, following a particularly frigid Sunday night.