Communities from Kempsey in the state's north to eastern suburbs of Sydney and Kiama south of Wollongong are assessing damage from heavy rain and strong wind over the weekend.

The Bureau of Meteorology is considering sending severe weather experts to several areas, including Kiama, where many houses were damaged.

Click or tap the photo below to see more photos and video of the storm damage across NSW

Experts debate whether the Kiama event was a tornado or a downburst from a thunderstorm. Josh Fisher, head meteorologist at Weatherzone, said the storm had the characteristics of a tornado from the radar observations: “It was a rotating storm over Kiama.”

Mohammed Nabi, severe weather forecaster at the weather bureau, though, said the straight-line nature of the event suggested it was a thunderstorm downburst. More investigation will be needed to be sure, he said.

The north-east corner of the state can expect 25-50mm of rain today, potentially complicating recovery efforts for some towns.

The Weather Bureau and State Emergency Service expect the heavily populated Nepean-Hawkesbury valley to Sydney's north and west will face minor flooding later today, in part because the giant Warragamba Dam has hit capacity and is automatically releasing water.

A spokeswoman for the Sydney Catchment Authority said the dam, which has spilled 53 times in its 53 years, will continue releasing water for several days. The dam's water total increased 6 per cent in the past week alone.

The rainfall outlook suggests inflows into the Warragamba will continue to be high for days to come.

“For the next days, we are going to see thunderstorms over parts of western Sydney,” Weatherzone's Mr Fisher said.

“These thunderstorms could impact the Warragamba Dam and the flows into that.

“There is the potential for another significant band of rain to move through on Thursday.”

Despite the widespread floods hitting towns including Kempsey, insurers are yet to declare the event a catastrophe based on current claims.

The industry has already declared catastrophes for floods three weeks ago stretching from central Queensland to the mid-NSW coast, and bushfires in Tasmania and NSW, with total claims approaching the $1 billion mark for summer.

Yarras, west of Port Macquarie, had the highest rainfall during the past week. It recorded 415mm in the 24 hours to 9am on Saturday, breaking a daily record for the area that had stood for 64 years, the bureau said.

'The rain was unbelieveable': town wakes to devastation

Residents of Kiama, in the NSW Illawarra, awoke to scenes of destruction yesterday morning after a tornado ripped through the township leaving a trail of severely damaged homes in its wake.

Aerial photographs reveal the path the Kiama tornado took when it hit land at the south end of Bombo Beach around 3am.

From there it climbed up a hill through several residential streets before it caused maximum damage to homes at the highest point of Minnamurra Street.

WATCH: Storm damage in Kiama. Video: ILLAWARRA MERCURY

The storm system then continued south-west, damaging parts of a retirement village, and ripped roofs off the Kiama Fire Station and parts of the Kiama Leisure Centre.

The tornado continued across the Princes Highway into the Cedar Ridge Estate.

At least a dozen residents have been left homeless after their properties were completely destroyed, and others have been forced out by the discovery of asbestos.

Contractors will now work to make the area safe, a process which could take more than a week.

Gipps Street resident Darren Ritchie said a waterfront home on the north side of the street appeared to explode when the storm hit.

Mr Ritchie said he was woken by what sounded like a freight train around 3am and he ran to get his 18-month-old son.

"It lasted about a minute ... we escaped with just two broken windows, but the two holiday homes next door were severely damaged," Mr Ritchie said.

Further down Gipps Street former Sydney Morning Herald journalist Bruce Elder said he had always joked that he wanted to be in a tornado, but never thought he would be in one in Kiama.

The Elders had a window broken thanks to debris from the unoccupied house next door which had windows and a verandah ripped off at the front and windows smashed at the rear.

"The rain was unbelievable ... it was absolutely solid," Mr Elder said. "Then the wind started to build up and build up ... then the whole house started to shake."

Mr Elder's wife Kim is a former California resident.

"I have lived through earthquakes and they were nothing like this," she said.

At the highest point of Minnamurra Street residents were woken by a noise they described as being like a jet aircraft.

About five homes on the north side of the street were severely damaged with roofs and even rooms completely taken off by the winds, the bulk of the damage being caused to homes in a section of the street about 150 metres wide.

One woman had a lucky escape when the bedroom in which she was sleeping was the only part of her house to remain in place.

Debris and contents from the affected homes, from tiles to furniture, caused significant damage to cars and homes on the south side of Minnamurra Street.

The street was covered in broken tiles, wood, shattered glass, books and clumps of pink and yellow insulation which had been sprayed across cars like fairy floss.

'Worst flooding in years'

In Port Macquarie, on the NSW North Coast, homes have been evacuated, many properties inundated and State Emergency Service volunteers are stretched to the limit – tackling some of the worst flooding to hit the Hastings river in more than a decade.

Some communities remained isolated for much of Monday, after flood waters caused a Settlement Point ferry cable to snap. The ferry was operational again by mid-afternoon.

Riverside Drive resident Tim Hitchins said the majority of homes on the North Shore had been inundated.

“Most of the houses on the northern end of Settlement Point were filled with waist-deep water yesterday,” he said. “Even now on low tide there is still a lot of water.”

Mr Hitchins said many long-time locals believed this to be the worst flooding they’d seen in the area.

As of Monday afternoon, the SES was advising residents of Settlement Point and low-lying areas of the Port Macquarie CBD that it was safe to return.

Almost 200 of people passed through the local evacuation centre at Port Macquarie Panthers on Sunday, among them 67-year-old Doug Bolar from Rollands Plains.

With nothing but the boots on his feet, shirt on his back and a spare pair of jeans in his car, he was waiting to get back to his property. But despite having to resort to sleeping in the back of his four-wheel drive, Mr Bolar remained positive.

“I just think if I’m copping it, everyone else is copping it too,” he said. “What can you do – this is just a part of living in Australia.”

State Emergency Service Deputy Controller Rescue Michael Ward said  conditions were improving slowly, but water was not subsiding as quickly as expected.

“I've been here in town for seven years, and it's the largest event we've seen yet,” Mr Ward said.

Floods claim two lives

Elsewhere, rising floodwaters claimed two lives over the weekend with 17 year-old Luke O’Neill dying after being sucked into a drainpipe on Friday night as he was collecting golf balls in waist-deep water in the town of Kew.

As floors are swept, and sandbags are stood aside, locals will spare a thought for the Bonny Hills teen – the young sportsman described as “gifted” and “wonderful” – who tragically lost his life.

His death will resonate with a devastated community as they pick up the pieces after days of wild weather.

As heavy rain battered the region on Friday, the O'Neill and his friends were wading through waist-deep water at the Camden Haven Golf Club, on Kendall Road in Kew.

Police said the group of friends were simply searching for golf balls – as they had often done before – when the sheer force of the floodwater pulled Luke into a drainpipe.

Two friends searched for him, before one of them was also sucked into the pipe.

The 16-year-old emerged in a dam, after being swept through the pipe for 100 metres, but Luke was no where in sight.

Police said the 16-year-old was in a stable condition, with water in his lungs.

The following morning, a friend found Luke’s body lying in the reeds, some 40 metres away from the exit of the drain he disappeared down.

Early Saturday afternoon the body of a man was found in his submerged car on a flooded road at Mylneford, about 20km northwest of Grafton.

The Pacific Highway was closed in both directions between Grafton and Maclean and between Port Macquarie and Clybucca on Sunday morning but it had re-opened north of Macksville.

On Sunday afternoon, a Westpac Lifesaver rescue helicopter flew a family of eight, including a newborn baby, to Port Macquarie from a farm cut off by floodwaters about 30km west of Wauchope.

The chopper was also diverted to rescue a woman trapped in her car by floodwaters.

Meanwhile, a man had to be rescued when his car was washed off a river crossing at Casino on Sunday night prompting police to beg motorists not to cross flooded rivers.

Two Japanese tourists had to be rescued when they became stranded in a car on a causeway near Lismore and a family of seven had to be winched to safety when they became stranded on the Clyde River in Ulladulla where they were camping.

About 100 train passengers on the Countrylink XPT service from Sydney to Casino were trapped for nearly 17 hours after fallen trees, floodwaters and a landslide stopped the train three times before it reached Coffs Harbour at midday Saturday.

Weatherzone is owned by Fairfax Media, publisher of this website.