Roads are closing and farmers are starting to move livestock to safer ground as rain continues to lash New South Wales, causing rivers to rise.
The threat of renewed flooding is being felt particularly hard in northern NSW, which has flooded twice since the start of this year.
Minor flooding is currently occurring along the Wilsons River, which could affect Lismore later this afternoon.
Minor flooding is also occurring along the Richmond River, which will affect Coraki and Bungawalbin tonight.
The Bureau of Meteorology said the Wilsons River may reach the minor flood level of 4.20 metres today, but warned further rises could occur.
Recent rainfall along the Lachlan River catchment, combined with earlier flood peaks, have the potential to cause minor flooding at Booligal.
And minor flooding is also possible along the Richmond River at Coraki and Bungawalbin from today.
Tweed Coast Road at Wooyung on the Tweed Coast has also been closed due to flooding.
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Separate wet weather systems lashing opposite sides of country
Two wet weather systems are currently moving across opposite sides of Australia, with multiple states set for an absolute soaking – and chilly temperatures.
Western Australia and NSW will be lashed with more heavy rainfall over the next 24 hours as two separate cold fronts cause temperatures to plummet.
And residents across Sydney are being warned not to pack away the umbrellas just yet; The Bureau of Meteorology (BoM) said the city could be hit with 20-40mm of rain today.
The warnings come after 15mm of rain felt overnight.
The Harbour City has had more wet days than dry this year BoM said, with 94 of 142 recording rain.
Senior Meteorologist Jonathan How said wet weather will persist until Thursday.
"(We've seen) heavy showers and storms overnight," How said.
"These are likely to continue today.
"These are likely to continue today.
"We will see those showers get 10 to 20mm each day until at least Thursday; that's the next dry break for Sydney and the Central Coast."
A hazardous surf warning is also in place for Byron Coast, Coffs Coast, Macquarie Coast, Hunter Coast, Sydney Coast, Illawarra Coast and Batemans Coast, until Tuesday at least.
The Sunshine Coast in Queensland also received a drenching, recording 51mm of rain at the airport.
Showers are also expected to fall across Queensland today as well, Brisbane has 4 to 10 mm of rain forecast.
The cold front is lowering mercury levels across the east-coast, with frost warnings in place for Victoria's Northern Country, central, west and south east Gippsland.
Metropolitan Victoria is set to hit 17C on Monday and 18C on Tuesday.
The Bureau is predicting Queenslanders to experience mild mornings with temperatures dropping to 15C.
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'Vigorous cold front' hits WA
A severe weather warning is in place for southern WA with damaging winds and pounding rain to wreak havoc this afternoon and well into Tuesday evening.
This is due to a "vigorous cold front" sweeping across the state. Morning lows of 13C and 11C will be felt on Tuesday and Wednesday respectively.
In addition to the chill, the next several days will be "wet and windy", the weather bureau has warned.
Destructive wind gusts in excess of 125 km/h are predicted for the state.
The heaviest of the rain is predicted today; Perth could cop between 30 - 60 mm of rain.
Read on to find out what the weather is doing across the nation's capitals today.
Brisbane
There's a high chance of showers forecast for Brisbane today, with temperatures set to hit a maximum of 22C.
Rain is most likely to hit the city from late morning, persisting into the afternoon.
Sydney
The Harbour City is instore for showers and a maximum of 19C.
The BoM said there's even a chance of a thunderstorm neaar the coast.
Melbourne
Meanwhile in Melbourne, cloud is clearing. This will give way to a sunny, 17C day.
Canberra
It will be a partly cloudy, 16C day in Canberra; perfect conditions for Prime Minister-elect Anthony Albanese's swearing in.
Hobart
It will be mostly sunny but chilly in Hobart. Temperatures will reach 15C.
Adelaide
It will also be sunny in Adelaide. It will reach a maximum of 22C.
Darwin
The mercury will soar to 34C in Darwin. It will be a mostly sunny day.
Perth
Storms and possible heavy falls are are possible in Perth. The temperature will reach a maximum of 17.
