Extreme heat, whether occurring as single or multiple anomalously hot days and nights, poses direct and indirect impacts to human health and to built and natural systems. Direct impacts include heat-related illnesses (e.g., heat cramps, heat exhaustion, heatstroke) and mortality. Indirect impacts include exacerbations of other hazards, like drought and wildfire, as well as stressors like air pollution. Adaptation to extreme heat can take many forms, such as in behavioral, institutional, infrastructural, technological, and ecosystem-based change. It can also take place on varying levels or spatial scales, requiring different resources and time frames to implement. Given that heat-related illnesses and mortality are often preventable when people are able to take protective action, one potentially near-term, relatively cost-efficient, and effective adaptation is to successfully inform the public about heat risk. This requires not only communicating with the public about heat risk when it is imminent (i.e., institutional adaptation), but also educating the public about heat risk such that it can interpret and make use of the messaging received (i.e., behavioral adaptation). The field of risk communication offers recommendations and guidance that can help inform heat risk communication, for example related to warning source and channel as well as to message purpose, content, and style. Similarly, the field of health literacy, and in particular the newly conceptualized “climate and health literacy,” offer proposed pathways that can be leveraged to help educate the public about heat risk. Bridging these two fields and the actors (or practitioners) within them therefore promises to be fruitful in the reduction of heat-related morbidity and mortality and in improving overall health outcomes in vulnerable populations across the globe. Critically, however, to be effective, both risk communication and climate and health literacy must be designed with direct knowledge of and engagement with target audiences. Accordingly, actors within these fields should collaborate not only with one another but also with the specific audiences they intend to serve.
