Clearly communicating heat warning information to the public is an important way to reduce heat mortality and morbidity. However, heat communication interventions from the National Weather Service commonly include technical and scientific terms, otherwise known as jargon. These terms, such as heat advisory or heat index, may not be understood by the public.

Given the importance of message understanding in protective action decision making, the purpose of this study is to assess how the public understands National Weather Service heat information. Specifically, we asked 195 participants recruited via Amazon MTurk what the terms excessive heat watch, excessive heat warning, heat advisory, and heat index mean to them. This approach allows us to (a) evaluate how these terms are understood by examining how people give them meaning, and (b) determine if they are jargon by comparing the meanings between the National Weather Service and the public.

Our results show that these terms mean something different to the public than the National Weather Service. Almost half of participants reported heat index was synonymous with air temperature, with less than 10% of participants indicating that heat index includes humidity. Furthermore, the timing of heat watches, warnings, and advisories was inconsistent with National Weather Service definitions. To address these differences in understanding, we suggest that researchers and practitioners explore plain language messaging alternatives to improve future heat communication from the National Weather Service and weather enterprise more broadly.