Almost 24,000 people in NSW have been cast from their homes but the torrential rain that has battered the state for the past week has finally eased.

About 60,000 people have nevertheless been told by the State Emergency Service to be ready to evacuate, with major flood warnings still in place for the Macintyre, Gwydir, Clarence and Hawkesbury, Nepean and Colo rivers.

There have been 11,000 calls for help to the SES so far, and 950 flood rescues.

A Pakistani national on his first day of a new contracting job died after his car was trapped in flood waters at Glenorie.

Premier Gladys Berejiklian expressed her condolences to the man's family, as did Prime Minister Scott Morrison and Opposition Leader Anthony Albanese.

Mr Morrison labelled Wednesday a "terribly sad day".

"We have seen so much over the course of the past year and more as this country has battled so many things - floods, fires, viruses, drought and now these floods again," Mr Morrison told federal parliament.

The Bureau of Meteorology predicts there will be no major rain for at least a week, barring up to 40mm on the NSW south coast on Wednesday.

The reprieve paved the way for defence personnel and emergency service workers to get essential supplies to isolated communities, particularly North Richmond in Sydney's northwest.

Ms Berejiklian said the state remained in crisis despite the sunnier weather.

She says the damage inflicted on thousands of homes, businesses and infrastructure means life will be significantly disrupted for many people.

Some catchments are experiencing their highest water flows in 50 years.

"What we are seeing before us in NSW is the unfolding of human tragedy ... tens of thousands of people who will go back and never have the same experiences again," Ms Berejiklian said in NSW parliament.

The areas of continued concern include Moree in the NSW northwest, the Upper Hunter around Singleton, Grafton, parts of the Central Coast, and the Hawkesbury-Nepean catchment northwest of Sydney.

Flood evacuation orders have been issued for people living in low-lying areas of Ulmarra, Brushgrove and Cowper on the Clarence River in northern NSW.

BOM meteorologist Victoria Dodds said flooding won't recede until the weekend, particularly on the "complicated" Hawkesbury-Nepean Valley river system which restricts water flows at some points.

The bureau also warned of the risk of falling trees due to saturated soil.

"River levels are still really high, we still have major flooding, it's a very protracted flood event," Ms Dodds told reporters.

SES Commissioner Carlene York said the reprieve in the weather would allow supplies to be delivered to isolated communities via boat and helicopter.

She said those evacuated must prepare to confront devastating scenes when they return to their homes, which will be sodden with water and mud.

Deputy Premier John Barilaro will co-ordinate the clean-up efforts.

Police Minister David Elliott said there were 1600 SES volunteers involved in the crisis as well as the ADF, which was offering helicopter support and troops on the ground working "hand in glove" with the SES.

The ADF will initially deploy 300 personnel, rising to about 700, to help with the grunt work when floodwaters subside - clearing debris, sandbagging, cleaning-up as well as helping to restore essential services.

There have been 12,000 insurance claims to date and that number is expected to increase dramatically, with the government promising it will be vigilant in holding insurers to account on processing claims.

Elsewhere, 189 schools remain closed but flights to and from Newcastle Airport resumed at midday after the runway was shut on the weekend.

The SES also warned the flooding of sewerage pumping stations in the Nepean area had discharged raw sewerage into surrounding floodwaters.

Australian Associated Press