This guidance provides information on the nature and effects of extreme heat.1 As the humanitarian experience of extreme heat is still fairly limited, this information should be useful in helping readers to better understand key aspects of the threat. The information provided is based almost exclusively on peer-reviewed literature, prioritising literature that concentrates on low-income contexts and that reviews multiple sources (systematic and scoping reviews). 

The guidance also identifies concrete actions that humanitarians can take – specifically in the sectors of Food Security and Livelihoods (FSL); Health; Nutrition; Risk Communication and Community Engagement (RCCE); Shelter; Water, Sanitation and Hygiene (WASH); and Protection – to prepare for and respond to heatwaves. (From the document.)