Hot weather becomes a heatwave when the maximum and minimum temperatures are unusually hot over three days and don’t drop much during the night. A heatwave isn’t just a day of soaring temperatures, it’s dependent on how long the heat lasts and how much it cools down at night.

Heatwaves are split into three categories – low-intensity, severe and extreme. Low intensity is the most common and bearable for most people, severe heatwaves become challenging for vulnerable people, and extreme heatwaves affect infrastructure like power and transport, can cause blackouts and are dangerous to anyone who doesn’t take precautions.

Heatwave. It’s a word that conjures up scorching seatbelt buckles, sweaty armpits, and a desire to immerse yourself in cold water or recline in an air-conditioned room.

What causes heatwaves, why are they so dangerous and what can we do about them?

Heatwaves can impact people, nature and infrastructure.

Heatwaves can impact people, nature and infrastructure.

What causes heatwaves?

Heatwaves are caused by high pressure systems transporting hot air toward a specific location. But while heatwaves themselves are natural, the increasing frequency, intensity and duration of them is not.

Climate change is the biggest driver of heatwaves, and companies extracting, processing and burning fossil fuels including gas are the biggest drivers of climate change. While big polluters profit, deadly and destructive heatwaves are hurting the people, places and animals we love.

2024 was officially declared the hottest year on record and the first year the average temperature exceeded 1.5 degrees Celsius above pre-industrial levels. As companies continue to burn fossil fuels, we can expect to continue to see heatwaves, extreme weather events and drought become more widespread and more frequent.

Why are heatwaves dangerous?

Heatwaves can be deadly. In fact, severe and extreme heatwaves have killed more people in Australia than any other natural hazard. Kids, grandparents, outdoor workers, and those with health problems are most at risk.

The danger of heatwaves also goes beyond our personal safety.

Heatwaves can damage infrastructure, disrupting power supplies and transport systems. Corporates and governments have underinvested in our transport networks and our energy grids, including ageing coal power stations now struggling to operate in this unnatural heat. 

They can also impact our economic environment, damaging crops and harming livestock, interrupting supply chains and causing energy system failures.

Then there is the impact on our beautiful natural world. All wildlife can be impacted but particular animals like birds, bats and fish are particularly susceptible, with mass deaths known to occur during heatwaves. Heatwaves can also make bushfires and drought more likely which can be catastrophic for our threatened species.

Lewin's honeyeater bird, drinking water from dish on backyard deck.

Lewin's honeyeater, drinking water from a dish on a backyard deck.

Caring for wildlife during a heatwave

Our beautiful native animals are doing it tough. Not only is climate change increasing the frequency and intensity of heatwaves, but much of their habitat is being bulldozed to the ground. This means for there are less and less safe places for them to retreat to in scorching weather.

But you can help! If you see animals suffering from heat stress, ensure you keep your pets away, put water nearby, monitor them from a safe distance and call your local wildlife rescue for further advice.

We’ve put together a comprehensive guide on how to support wildlife during and after heatwaves and bushfires.

So, what can we do about heatwaves?

Heatwaves may seem like something out of our control, but we can still reduce their severity and impact.

Australia’s leaders must put the brakes on the summers of chaos and commit to rapidly cutting climate pollution by:

  • Stop the climate wreckers: no more green lights for big coal and gas polluters.
  • Champion renewables: cut pollution and power everything we can with clean, cheap energy from wind and sun.

Sign the pledge for climate and nature and tell the people that want to represent you they must be ready to solve the extinction crisis to get your vote.

Pledge your vote

Australian Conservation Foundation