A massive bushfire on the NSW South Coast that destroyed homes and claimed the lives of several people has been declared extinguished after this weekend’s heavy rain.

The NSW Rural Fire Service last night said the Currowan Fire in the Shoalhaven had been officially set to ‘out’.

For 74 days the fire burnt out 499,621 hectares, destroying 312 homes in towns, including Lake Conjola.

It comes as heavy rain continues to fall across much of the state.

The Bureau of Meteorology (BOM) issued a severe weather warning extending the length of the coast, with torrential rainfall and damaging winds of up to 90 kilometres per hour expected.

The powerful winds, rain and a king tide are expected to cause erosion along parts of the coast.

Massive waves were seen moving up a cliff face at Kurnell, creating what has been described as a “reverse waterfall”.

Senior forecaster, Jenny Sturrock, said the bushfire-ravaged South Coast region had already copped a drenching but would receive heavier rainfall today.

“We’re expecting some heavier falls of 100 to 150 millimetre … along the South Coast, so we are expecting a slight easing I guess if you will through the Far North, but still some fairly decent falls of up to 100 millimetres are possible,” she said.

At least 17 people have been rescued from flood waters in New South Wales.

Todd Burns from the State Emergency Services (SES) said most of those rescued were inside vehicles after driving through flood waters.

“The total number of jobs for this week’s weather event has increased to more than 3250 — more than 500 of those jobs happened last night.”

To date, most of the call outs have been in Sydney but crews will focus on the Illawarra today, where up to 250 millimetres of rain is forecast.

A gale warning is in place for the coast Macquarie Coast, Hunter Coast, Sydney and closed waters, and the Illawarra Coast, while there’s a strong wind warning for the Coffs Coast, Batemans Bay and Eden.

Authorities say the weather system will help top up Sydney’s water catchments.

Warragamba Dam has been at 46 per cent capacity but Water NSW said parts of the catchment across the Blue Mountains had received more than 150 millimetres of rain.

Adrian Langdon from Water NSW said farmers were also cheering with some parts of the state receiving their best rainfall in almost a decade.

“For some of those agricultural areas that have been extremely dry for the last three to five years, [they’re] getting some good rainfall as well.”

The BOM said winds would generate large, powerful rains in combination with king tides which could lead to significant coastal erosion.