The federal government has declared NSW's latest floods a natural disaster, activating emergency funding support. 

Federal Emergency Management Minister Murray Watt says payments will be available for residents in 23 local government areas affected by the crisis across Metropolitan Sydney, the Hawkesbury, Central Coast and Illawarra.

“These are uncapped payments, they are demand-driven and they will be available for anyone who qualifies,” Mr Watt said.

A deluge continues for Sydney and NSW, with authorities urging residents to stay vigilant of flash flooding as rivers continue to rise. Some locations have received up to 800 millimetres of rain over four days. 

Reports say there have been over 5,000 requests for assistance since the beginning of the emergency, 252 of which were flood rescues. There has been one confirmed fatality so far.