Prepare for summer flooding: NSW premier

Premier Dominic Perrottet has told communities to prepare for more chaos, with new storms set to roll across the state's southeast this weekend.

More than 70 NSW local government areas are currently subject to disaster declarations. 

There are 23 emergency warnings in place and the SES  says communities need to be prepared for potential flash flooding and continued major riverine flooding in many of the state's catchments.

"The rivers are full, the dams are full, the catchments are full, the ground is wet," Mr Perrottet said on Friday.

Touring the devastated central western town of Eugowra, Mr Perrottet pledged support to rebuild flooded communities.

"What I have seen everywhere I go across the state, is we get through it and we rebuild, and the communities come back and they come back stronger," he said.

Relief payments for affected farmers were increased on Friday and caravans will soon be brought in to temporarily re-home Eugowra's evacuees.

"We will ... put people back on their home blocks, even if their home is not habitable, in a caravan if they so choose," Emergency Services Minister Steph Cooke said.

Meanwhile, major flooding is expected to continue along several river systems, including the Lachlan, Darling and Murrumbidgee, affecting towns including Forbes and Condobolin in the central west, Bourke in the northwest and the Riverina town of Hay.

Prolonged major flooding in Forbes isn't expected to ease until early next week.

Downstream, Condobolin and Euabalong are bracing for the worst after the Lachlan River rose beyond records set there in 1952.

After a brief respite, a rain system will return to Australia's eastern states on Saturday, bringing showers and thunderstorms.

The Bureau of Meteorology Bureau said Victoria and Tasmania would bear the brunt of the system along with NSW on Saturday before easing into Sunday.

Come Monday, southern South Australia, Victoria, Tasmania and southeastern NSW can expect widespread showers, possible hail and thunder.

With some rivers in flood for the past six months, NSW State Emergency Service chief Ashley Sullivan said affected residents should expect the situation to continue through Christmas and into the new year.