Heatwave

Name: Heatwave
Start: 0001-01-01
End: 0001-01-01
Location: National

Discover related resources in the Understanding Hazards Collection and on the Big Weather page

What is a heatwave?

A heatwave occurs when the maximum and the minimum temperatures are unusually hot over a three-day period in a specific location. This is considered in relation to the local climate and past weather at that place.

It takes more than just a high daily maximum temperature to define a heatwave. It's also about how much it cools down overnight. If the temperature stays high overnight, the maximum will be reached earlier the following day and will last longer. When unusually high night and daytime temperatures persist, heat stress becomes a critical factor in human health and whether infrastructure functions properly. In heatwaves, hot nights make it harder to recover from the heat of the day and this puts more stress on the body.

Heatwaves are classified into three types, based on intensity.

Low-intensity heatwaves are more frequent during summer. Most people can cope during these heatwaves.
Severe heatwaves are less frequent and are likely to be more challenging for vulnerable people such as the elderly, particularly those with medical conditions.
Extreme heatwaves are rare. They are a problem for people who don't take precautions to keep cool – even for people who are healthy. People who work or exercise outdoors are also at greater risk of being affected.

_{(Understanding heatwaves, Bureau of Meteorology; BOM Weather Guide: Heatwaves, Bureau of Meteorology)}

Risks

Severe and extreme heatwaves have claimed more lives than any other natural hazard in Australia.

The bulk of heatwaves at each location are of low intensity, with most people expected to have adequate capacity to cope with this level of heat. Less frequent, higher intensity heatwaves are classified as severe and will be challenging for some more vulnerable people, heatwaves can be dangerous because they post health risks to the most vulnerable people, such as the elderly and very young children.

Extreme heatwaves are a risk for anyone who does not take precautions to keep cool, even those who are healthy. Heatwaves can also affect the transport, agriculture and energy sectors and associated infrastructure.

_{(About the heatwave service, Bureau of Meteorology; Understanding heatwaves, Bureau of Meteorology)}

Heatwave Knowledge Centre | Bureau of Meteorology

Learn more about heatwaves, heatwave forecasting and warning, and how to be prepared.

Make an emergency plan | Australian Red Cross

Find simple, practical tips for how to protect yourself, the people you love and the things you value most.

Prepare, plan and stay safe

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Let's think about heat - International Heat Action Day webinar

In 2022, Red Cross internationally launched Heat Action Day, a campaign to promote action to reduce the impacts of extreme heat.

This webinar features a range of speakers and cover the impacts of extreme heat, how we warn people about heat, how we can reduce the impacts of heat and understanding the mental health impacts of heat.

Webinar Host: John Richardson, National Resilience Advisor, Emergency Services, Australian Red Cross

Guest Speakers:

Dr Roop Singh, Climate Risk Advisor, Red Cross Red Crescent Climate Centre
Bradley Santos, Bureau of Meteorology
Alana Pedler, Operations Coordinator, Red Cross in South Australia
Jingwen Liu, PhD Candidate, University of Adelaide
Blesson Varghese, University of Adelaide and SA Health