The current weather conditions are brewing up a perfect storm for not one but two species of shark in the water off Sydney's beaches.

Shark expert Dr Chris Pepin-Neff told Today that the combined factors of recent rain and sea temperatures mean both bull sharks and great whites are being lured closer to shore.

Pepin-Neff said sea surface temperatures of 20 degrees and above were ideal for bull sharks, while 20 degrees and below was perfect for great whites.

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And right now, "we're right in the middle".

"It's the end of May, we're right at that seasonal point," he said.

Added to that, recent heavy rain had stirred up brackish water closer to the shore, which also made ideal hunting conditions for bull sharks.

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And great whites were being drawn in closer by the cooling temperatures.

"I want surfers to be aware if you're in the Northern Beaches, if you're doing surfing right now, white sharks are in closer," Pepin-Neff said.

He urged surfers to stick together in groups in the water for safety's sake.

Other swimmers were told to stay out of brackish water, and if they were swimming at an ocean beach, to stay between the flags.

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Pepin-Neff said the noise generated in the water by a group of people could intimidate sharks and keep them at a distance, so there's safety in concentrated numbers.

Sydney recently saw a spate of attacks believed to have been carried out by bull sharks, in January this year.

Among the victims was 12-year-old Nico Antic, who was fatally mauled and died in hospital.

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It might not seem like it right now, but Australia ranks among the richest countries in the world.

Financially speaking, Australians live in a "lucky country". Our nation is home to the 12th-largest economy, which is thriving partly because we are a global resource powerhouse.

So why does it sometimes feel like we don't have much money?

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According to AMP's deputy chief economist Diana Mousina, crushing household debt is to blame.

Australians have some of the highest levels of personal debt in the world, mostly due to soaring house prices and inflated mortgages.

The average household debt is around 210 per cent of disposable income.

This is much higher than comparative economies such as the US, New Zealand, Canada and Japan.

The only countries with higher debts are Norway and Switzerland.

Mousina said this is because of our enormous mortgage market.

Rising loan repayments are squeezing Australians at a time when everything else is getting more expensive too.

"Australians have a strong preference for home ownership, both for living and investment," Mousina said.

"High debt levels do increase vulnerability.

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"Households are more exposed to rising interest rates, which lift repayment costs, and to economic downturns, where job losses can make servicing debt more difficult."

On the bright side, our penchant for owning large, appreciating assets will only be a boon in the long run.

Stockpiles of wealth like land and property "provides a buffer" for the debt hanging over families, Mousina explained.

"On this measure, Australia looks strong, with household wealth at around 513 per cent of income," she added.

And despite the alarming statistics, Mousina said Australian household debt has actually slowed in the past few years.

While the consecutive rate rises and threats of a looming recession have been a blow to consumer confidence, the economist has a sunny outlook for how we can weather any future economic pain.

The biggest problem might actually be our warped perception.

"Have Australians become so used to the 'good times' that we don't even remember what hard economic periods are like?" Mousina asked.

"The reality is that Australia remains a high-quality economy, with strong institutions, a stable financial system and relatively moderate policy settings.

"Perhaps the issue isn't just the economy itself – but how we perceive it."

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How does Australia rate on the global happiness scale?

We might have a lot of personal debt, but Australians are much happier than many of our neighbours.

According to the World Happiness Report, Australia is the 15th happiest country in the world – sitting ahead of countries including US, Germany, France, Singapore, Italy and Canada.

The report ranks nations based on their GDP, freedom, welfare systems, job security and perceptions of corruption.

Given Australia's healthy happiness scorecard, Mousina said it is "somewhat surprising" that the economic sentiment is so negative.

"Based on these measures of living standards, Australia generally comes out relatively well – a country with strong fundamentals and solid long-term prospects."

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