This State Emergency Management Plan (SEMP) Extreme Heat Sub-Plan contextualises the current arrangements, roles and responsibilities for planning, mitigation, preparedness, response (including relief) and recovery from all extreme heat events, regardless of their duration. For the purposes of this Sub-Plan, extreme heat events include low-intensity, severe and extreme heatwaves (three or more consecutive days of high temperatures), or one or two days of abnormal high temperatures which would impact the general population and include consequences for essential services, energy and water supply, health and wellbeing and the environment. The metric for defining heatwaves is the Excess Heat Factor (EHF), which correlates to one of three heatwave levels: low-intensity, severe or extreme heatwaves (see section 2). Operational activities of agencies or businesses are covered within their respective operational plans. Agency specific operational or business continuity plans may be enacted to manage the impacts or consequences of extreme heat events, without state level arrangements being triggered.