A heatwave is a period of unusually hot weather, when both daytime and nighttime temperatures stay higher than normal for at least three days.
It’s not just about how hot it gets during the day — it’s also about how much it cools down overnight. When nights remain hot, our bodies don’t get a chance to recover, increasing the risk of heat-related illness.
Extreme heat can affect anyone, but older people, young children, and those with existing health conditions are most at risk. Heatwaves can also impact essential services such as power supply, transport, and health systems.
To help communities stay safe, heatwave warnings are issued when extreme heat is forecast. These warnings include expected temperatures, when the heatwave will peak or ease, the areas affected, and recommended actions to take. In Victoria, the Chief Health Officer may also issue a heat health warning when conditions pose a risk to public health, even if it’s for a single day of very high temperatures.
View Better Health Victoria's video on extreme heat.