'VERY DANGEROUS': Aussies warned about heavy rain, more flooding

Australia's eastern states are bracing for more "dangerous" wet weather and potential flooding as the country's ongoing La Niña conditions show no signs of abating.

Widespread rainfall fell across an already soggy NSW in the past 24 hours to Saturday morning with Lowanna in Coffs Harbour recording the state's highest total with 99mm.

"More rain and thunderstorms are expected today with heavy falls possible. Keep up to date with flood warnings as river rises are expected," the NSW Bureau of Meteorology warned on Saturday morning.

With the ominous forecast looming over the east coast in the coming days, Ian Wright, a senior lecturer at and researcher in water and environment at Western Sydney University, described conditions as "very dangerous".

"With so many regions experiencing flooding, the rain forecast for the next weeks looks very dangerous," he tweeted on Friday.

Communities in NSW are bracing for flash flooding with heavy rain and thunderstorms to hit many parts of the state this weekend.

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The SES performed more than a dozen rescues and answered hundreds of calls for assistance overnight while ninety-nine flood warnings remain in place across the state on Saturday morning.

The focus of the crisis continues to be in the state's far northeast and southeast, close to the Victorian border.

In the north, emergency warnings are in place for Moree, Narrabri and the hamlet of Terry Hie Hie, while in the southern borderlands an evacuation order is current for Moama.

The Bureau of Meteorology warns the big wet will likely continue, with widespread showers and thunderstorms forecast for eastern NSW, resulting in flash flooding for many regions.

The bureau says the northeast is an area of concern as a trough and possible low-pressure system develops off the coast, bringing heavy rain to the Northern Rivers, including Lismore and Byron Bay.

"Exact rainfall amounts will depend on where this trough forms and how it moves and in particular whether the low-pressure system develops near the coast or further offshore," it said late on Friday.

"Heavy rain may bring both a flash flooding and riverine flooding risk."

The bureau has forecast rain and storms on Saturday further south, including Sydney, where it predicts a thunderstorm will bring heavy falls causing flash flooding.

Residents in the city's west are expected to bear the brunt, with flooding tipped on the Hawkesbury and Nepean rivers.

Further ahead, the bureau says there will be "some brief reprieve" from the rain towards the middle of next week but flooding will continue regardless.

"Major flooding will continue across inland NSW and northern Victoria as floodwaters continue to impact travel, roads and infrastructure," it said.

Queensland meanwhile is facing a similarly treacherous weekend with totals of up to 200mm forecast in parts of the state from today into Sunday.

"Dangerous and life-threatening flash flooding possible," authorities warned on Saturday.

with AAP

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