Large parts of the New South Wales coast will soon be hammered by a fast-moving coastal low which is forecast to be a "complex" and "vigorous" system unlike other weather events Australia has seen recently.

The Bureau of Meteorology has warned rainfall up to 200mm, damaging winds, hazardous surf and coastal erosion will impact millions of residents in NSW.

Wild weather is set to travel down the mid-north coast of Coffs Harbour as far south as Bega, with Sydney also bracing for wet conditions not seen since 2022.

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Why is this east coast low so severe?

According to Weatherzone, a weather event known as explosive cyclogenesis is brewing off the NSW Mid North Coast – a process which rapidly intensifies the weather of an east coast low as it approaches land.

A few things stir up an east coast low and can make its coastal approach so damaging.

This includes warm sea surface temperatures, a blocking high-pressure system, temperature instability in the air and an upper trough developing over the Great Dividing Range.

An east coast low is so unusual because it can evolve quite rapidly.

The low develops into a strong low-pressure system, which in turn has quite a large impact with heavy rain, strong winds and wild surf, causing coastal erosion.

These weather systems also only develop near the coast and generally last a minimum of 12 hours.

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Where is it going to hit hardest?

The NSW State Emergency Service (SES) has issued a warning for anyone living on the coast between Coffs Harbour and Bega, including metropolitan Sydney.

However, some regions will see more rainfall, gale-force winds and damaging surf.

NSW SES Deputy Commissioner Debbie Platz today said the SES has deployed more personnel and resources into the most impacted areas, including Kiama, Albury, Hawkesbury, Maitland and Dungog.

Helicopters and emergency vehicles have also been directed to Taree, which was hit by a flood disaster in May.

"This is a time for our communities across NSW to be very vigilant and very prepared. We're looking at thunderstorms, rain, strong winds, coastal erosion and damaging surf," Platz said.

How much rain will we get?

Around 50-120mm of rainfall across the NSW coast is likely, but there is the chance of isolated totals reaching 150-200mm, the Bureau of Meteorology's Steve Bernasconi warned.

While some rain and wind is expected today, the heaviest weather is expected to hit tomorrow, particularly in Sydney.

Up to 90mm of rain is forecast for the NSW capital in just 24 hours and up to 140mm in total is forecast to lash Sydney over the next few days.

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What should I do to prepare my home?

The NSW SES urged impacted residents to prepare for cyclonic conditions.

"We are prepared here, at SES," Platz said.

"But what we need is for you to be prepared.

"You out there in the community need to start preparing for this weather event."

Platz warned people to clean gutters, to move or tie down loose items like outdoor furniture and trampolines and to move cars away from large trees.

Residents have also been urged to stay informed via the BoM and SES websites.

Platz urged people to download the Hazards Near Me app too.

When will conditions ease?

East coast lows often intensify quickly over 12 to 24 hours, the bureau said.

Heavy rain and damaging winds are expected to ramp up by tonight, with the most intense weather set to smash the coast by Tuesday afternoon and into Wednesday morning.

The east coast low is forecast to ease by Thursday, however the bureau said the wild weather could hang around until at least Friday.

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A Sydney mother has shared a warning after her son had a scary reaction to a henna tattoo while on a family holiday in Indonesia.

Kerrie-Anne Graf told 9news.com.au she and her 13-year-old son were at Kuta Beach, on the south-west coast of Bali last month, when they both made a spur-of-the-moment decision to get a henna tattoo.

The henna tattoos worked out great and were a big hit with her son, Graf said.

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However, a few days later, the pattern had started to fade. 

So, when the family was at Seminyak Beach and some locals came past touting henna tattoos for $10, her son asked if he could have the tattoo on his arm redone, Graf said.

"These guys just walk up and down the beach and they've got their book with dragons.

"You're there with your kids and they're saying, 'Mum, I want a tattoo'."

Unlike the first henna tattoo she and her son got, which was a traditional brown colour, the second tattoo on her son's leg was black, Graf said.

"He got it done the day before we left Bali and it seemed fine," she said.

"Then he started itching at it and, maybe two days later, it just blew up."

Graf said her son's arm became extremely swollen and developed a rash.

"At first, I just thought maybe it was nothing serious. But then the rash started to spread up his arm," she said.

When her son was sent home from school because his arm was weeping, Graf took him to the GP, who prescribed antibiotics.

"They did nothing, so we went back and he got a double dose of really strong antibiotics," she said.

In addition, Graf said her son needed to take steroid medication, antihistamines and apply cream to his arm.

"I've spent over $140 on medication," she said.

Graf said she wanted to warn other families travelling to Bali about the risk of henna tattoos.

After making a post on a popular Bali travel Facebook page, Graf was inundated with comments from other Australians who had suffered similar reactions to henna tattoos in Bali.

A 2019 investigation by 9News examined the dangers of "black henna" tattoos offered in Bali and found they were leaving some Australian tourists with permanent scars.

At the time, 9News found the "black henna" used by some operators in Kuta was made from hair dye containing paraphenylenediamine (PPD), a chemical that as many as one in five people are allergic to when it's applied to their skin.

Graf said she believed it was this black hair dye that was applied to her son's skin.

"It shocked me because I had never heard of that happening."

The mum said she was still very worried her son could be left with permanent scars.

"I can't put anything on it yet, like Bio Oil, because I think it will just irritate it more.

"So I'm just going to wait, and we're probably going have to see a dermatologist."

Graf she said hoped sharing her son's experience would make other tourists think twice.

"I wanted to say something because I don't want this to happen to any other kid," she said.

Millions of Australians on the east coast should brace for a "vigorous" weather system from tonight, which is forecast to bring several days of heavy rain, damaging surf and strong wind.

The coast of New South Wales from Coffs Harbour all the way to Bega in the south is expected to be hit with a fast-moving coastal low and the Bureau of Meteorology warned it may also hammer the Sydney metropolitan area.

"This is a very dynamic and fast-moving system, very different to the systems that we have seen in recent times," NSW SES Deputy Commissioner Debbie Platz warned.

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Heavy rain and damaging winds are expected to ramp up by tonight, with the most intense weather set to smash the coast by Tuesday afternoon and into Wednesday morning.

Bureau of Meteorology's Steve Bernasconi said the low is deepening off the north coast right now and will likely evolve this evening.

Around 50 to 120mm of rainfall could drench the east, south and mid-north coast of NSW, including Sydney, and some isolated showers could reach up to 200mm.

"It'll bring widespread impacts. The position and the strength of the low will determine the duration and the severity of the impacts, which may persist into Thursday," Bernasconi said.

He said it has become a "vigorous coastal low" and is complex and dynamic, meaning it is difficult to forecast just how severe the weather will be.

The NSW SES urged impacted residents to prepare for cyclonic conditions.

"We are prepared here, at SES," Platz said.

"But what we need is for you to be prepared. You out there in the community need to start preparing for this weather event."

Platz warned people to clean gutters, to move or tie down loose items like outdoor furniture and trampolines and to move cars away from large trees.

The Bureau of Meteorology has issued hazardous wind and surf warnings for the NSW coast.

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An initial flood watch warning is also in place for the Hawkesbury-Nepean, Georges, Cooks, Sydney Coast, and Illawarra Coast catchments.

The developing system has been dubbed a potential "bomb cyclone" – a rapidly forming system that goes from non-existence to threatening in just days.

It could also be the first east coast low to hit Sydney since 2022.

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While some rain and wind is expected today, the heaviest weather is expected to hit tomorrow, particularly in Sydney.

Up to 90mm of rain is forecast for the NSW capital in just 24 hours.

Sustained winds of 45km/h, with gusts of 125km/h, are predicted by the Bureau.

Stay up to date with warnings and conditions at the BoM and SES websites.

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Many Australian lottery winners aren't splurging their cash on big-ticket items like cars or houses after taking home their winnings, according to a new report.

The Lott surveyed division one winners from 2024 – who won a combined $1.56 billion – on how they spent their millions, and most said they either invested in the future or lavished family and friends with gifts.

More than half of the winners said they set themselves up for the future with investments, while 38 per cent said they helped out loved ones with their shock windfall.

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The Lott spokesperson Anna Hobdell said these results aren't surprising for division one winners, who take home life-changing amounts of money.

"Winners often tell us their bodies go into overdrive the moment they hear the life-changing news, with hearts racing, hands trembling, and even a wave of nausea setting in," Hobdell said.

"But once the news sinks in, most winners can't wait to share the joy with people in the know.

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"After the initial shock wears off, many winners are quick to tell their partners, family, or closest mates. 

"Only about eight per cent keep it completely under wraps and tell absolutely no one."

Plenty of lucky winners decided to buy some unique items, including a pair of hand-crafted leather shoes, a set of watches for their family, a hair transplant in Turkey, and some electric mountain bikes.

Another 33 per cent of winners said they bought a new car, but only 19 per cent reported buying a new house.

Some said they decided to travel the world with their newfound fortune, flying to destinations such as Thailand, Bali, Phuket, the Gold Coast and Alaska.

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And 17 per cent of the surveyed winners said they used their prize to donate to charity.

One newly deep-pocketed Aussie simply updated their old washing machine.

Reflecting on the life-changing injection into their bank account, a few winners also shared their advice for future lottery recipients.

"Treat your win as an opportunity to improve your circumstances, so don't waste it," one said.

"Tell very few people and write down who you told," another warned.

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People have been warned about trusting "Dr Google" for years – but AI is opening up a disturbing new world of dangerous health misinformation.

A new, first-of-its kind global study, led by researchers from the University of South Australia, Flinders University, Harvard Medical School, University College London, and the Warsaw University of Technology, has revealed how easily chatbots can be – and are – programmed to deliver false medical and health information.

In the study, researchers evaluated five of the most advanced and prominent AI systems, developed by OpenAI, Google, Anthropic, Meta, and X Corp.

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Using instructions available only to developers, the researchers programmed each AI system – designed to operate as chatbots when embedded in web pages – to produce incorrect responses to health queries and include fabricated references from highly reputable sources to sound more authoritative and credible.

The "chatbots" were then asked a series of health-related questions.

"In total, 88 per cent of all responses were false," UniSA researcher Dr Natansh Modi said.

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"And yet they were presented with scientific terminology, a formal tone and fabricated references that made the information appear legitimate.

"The disinformation included claims about vaccines causing autism, cancer-curing diets, HIV being airborne and 5G causing infertility."

Out of the five chatbots that were evaluated, four generated disinformation in 100 per cent of their responses, while the fifth generated disinformation in 40 per cent of its responses, showing some degree of robustness.

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As part of the study, Modi and his team also explored the OpenAI GPT Store, a publicly accessible platform that allows users to create and share customised ChatGPT apps, to assess the ease with which the public could create disinformation tools.

"We successfully created a disinformation chatbot prototype using the platform and we also identified existing public tools on the store that were actively producing health disinformation," he said.

Modi said that these findings revealed a significant and previously under-explored risk in the health sector.

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"Artificial intelligence is now deeply embedded in the way health information is accessed and delivered," he said.

"Millions of people are turning to AI tools for guidance on health-related questions."

He said AI systems could be manipulated to produce a powerful new avenue for disinformation that would be more persuasive than any other.

"This is not a future risk. It is already possible, and it is already happening," he said.

Modi said there was a path forward away from this scenario, but that developers, regulators, and public health stakeholders had to act "now".

"Some models showed partial resistance, which proves the point that effective safeguards are technically achievable," he said.

"However, the current protections are inconsistent and insufficient.

"Without immediate action, these systems could be exploited by malicious actors to manipulate public health discourse at scale, particularly during crises such as pandemics or vaccine campaigns."

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