Forster and Turncurry, twin towns about 200 miles north of Sydney, were cut off by high water, the Sydney Morning Herald reported. In Sydney itself, a few people were evacuated because of flood risk and two drivers had to be rescued when their cars became stuck on flooded roads.
Phil Campbell, a spokesman for the State Emergency Service, said about 1,000 calls from people seeking assistance came in in a 24-hour period.
At least one person has been killed. Luke O'Neill, 17, of Bonny Hill was sucked into a drain last weekend.
Eastern Australia endured a bad bushfire season. The week of bad weather kicked off with tornadoes in Kiama, 70 miles south of Sydney.
"It has been a very busy week for the SES," Campbell said.