NSW is in the grip of a prolonged, extreme weather event and threatened communities will not be out of the woods until the end of next week, Premier Gladys Berejiklian says.
The premier has put already flooded and vulnerable communities on an emergency footing, and says more evacuations will certainly be ordered.
People living on the mid-north coast, in the Hunter and Central Coast regions, in metropolitan Sydney, and in the catchment of Sydney's Warragamba Dam, must be on high alert, she says.
The premier says situation reports due by this evening will determine which communities will be ordered to leave their homes.
"Make sure if you are asked to evacuate you do so immediately. The window for evacuation is not a big one depending on where you live. Some communities already have been advised to stock up and stay home," Ms Berejiklian told reporters on Saturday.
"Within that window with a could potentially be cut off."
She said the danger would not pass until Thursday or Friday.
"It's not going to be an easy week for us but I know no matter what comes our way we will be able to deal with it."
Sydney's Warragamba dam is already spilling, with days more rain ahead. Even after the rain stops the water in the system means pressure on that dam will not ease for some time.
The premier said she had been briefed on the dam situation "in relation to a potential for a one and five year, one in 10 year, or one in 20 year event".
"All three scenarios being planned for."
The SES had been swamped with calls for assistance and has responded to 4000 call-outs and 500 direct flood rescues, something that has angered first-responders who have had to risk their lives to pluck people from cars driven into floodwaters.
