Heatwaves are generally acknowledged as a period of unusual and uncomfortable hot weather that could negatively affect human health.
The Bureau of Meteorology defines a heatwave as occurring when the maximum and the minimum temperatures are unusually hot over a three-day period at a location. This is considered in relation to the climate and past weather at a location.
Extreme heat can affect everyone; however, some people are more vulnerable. Extreme heat can also affect infrastructure such as electricity supply, transport (roads and rail) and other services resulting in power outages, delays or cancellations of rail services or failures of traffic management systems.
Examples of significant heatwaves in Victoria include:
- 2009 - consecutive days of temperatures above 43°C in late January followed by a record 46.4°C on 7 February culminated in the Black Saturday bushfires
- 2014 - hottest four-day period on record, from 14-17 January 2014.
Both heatwaves resulted in widespread impacts on the health system, public transport disruptions and power outages. The former Department of Health and Human Services released the January 2009 Heatwave in Victoria: an Assessment of Health Impacts report covering the health impacts of the heatwave incident in 2009.