Hundreds of homes across Sydney and the Illawarra region have felt the brunt of a series of "mini tornadoes" and flooding rains that have inundated much of New South Wales causing the Macleay River levee at Kempsey on the mid-north coast to be breached.


Port Macquarie is bracing for flooding with the Hastings River expected to peak this morning.


The State Emergency Service says Sydney's eastern suburbs were badly hit overnight, with 40 calls for help received from people in Malabar, Chifley and Randwick.


Eighty homes and a fire station were damaged at Kiama on the South Coast.


The SES has received 12-hundred calls for help, mainly from regions in northern New South Wales, Sydney and the Illawarra and has made 66 rescues.


Over 19-thousand people have been told to evacuate or to be prepared to.


Electricity supplier Ausgrid says about 17-thousand people were without power throughout the night in Sydney, the Central Coast and the Hunter regions.


The floods have claimed two lives with the body of a man found in his submerged car on a flooded road at Mylneford, about 20 kilometres northwest of Grafton yesterday afternoon.


And on Friday, a 17-year-old boy was killed after he was swept into a drainpipe while collecting golf balls in waist-deep water at Kew, south of Port Macquarie.


AAP