Reuters reports that a wild weather system that dumped more than two-thirds of annual rainfall over a week in several places in the most populous state of New South Wales (NSW) brought widespread destruction and led to evacuation orders.

6,000 more people were evacuated in the last 24 hours, NSW Premier Gladys Berejiklian said, while new orders were issued for affected residents in Sydney's western regions to move to safe zones.

"We do wake up to sunshine today in most parts of New South Wales which is a positive thing," Berejiklian told reporters. "But we're certainly not out of the woods in terms of the immediate flood danger, we have to turn our minds to how we start the clean-up and recovery."

Two were reported but more than 40,000 people in the state have been evacuated so far.

Rains eased from late Tuesday, leaving thousands of people displaced and sweeping away houses, farms, livestock and roads but the slowly swelling rivers remain a risk for many days.

"Large volumes of flood water are still making their way through the state's river systems and some communities are yet to see their flood peaks," the national weather agency said in a statement.

Though the rain band has moved south, the weather bureau said the "floods situation remains a serious threat to life and property across NSW and will continue to cause significant disruption and isolation."

The weather system will shift to the island state of Tasmania on Wednesday, authorities said, bringing heavy rains and localised flooding in several places over the next few days.

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