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Oh, yeah.
Australia's deadliest natural disaster isn't flooding, bushfires or cyclones.
It's heatwaves.
So why are heatwaves so dangerous?
A heatwave is when temperatures stay unusually hot for at least three days in a row.
Earlier this year one blasted Queensland, WA and New South Wales with 40 degrees Celsius heat, not cooling down much overnight either, sending hospitals into overdrive.
Between 2016 and 2019, more than 1,000 Australians died because of heat waves.
The danger is brutal.
The new National Climate Risk Assessment warns that under three degrees of warming, heat-related deaths in Sydney could soar by more than 400.
Why?
Because extreme heat pushes the human body past its limits.
Our core temperature needs to stay around 37 degrees Celsius.
In a heatwave, your body's cooling system that's sweating and pumping blood to the skin gets overwhelmed.
The heart pounds harder to move, more blood toxins leak from the gut to the blood and even into the brain.
The immune system goes into overdrive and vital organs are starved of oxygen, as blood is redirected to the skin to try and cool you down.
The brain can swell, kidneys can fail and heat stroke can kill in a matter of hours if untreated.
And the risks aren't equal either.
Older people, younger kids and people with existing health issues are most vulnerable.
Rural communities, like on farms, suffer when hospitals are far away and families in low income areas can be trapped in hot housing with air conditioning too expensive to run.
So what can we do?
Stay hydrated, rest during the hottest hours of the day and never ever leave kids or pets in cars.
You can check on your elderly neighbours and, if your house is sweltering, head to a cool public space like a library or a shopping centre.
Heatwaves are silent killers, but with preparation and action, we can keep cool and stay safe.
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On next week's Squiz Kids Science Shorts.