Contextualizing the Human Health Impact of Extreme Temperature Events Using Intensity-Duration-Frequency Curves

While dry-bulb temperature remains a familiar method for communicating heat hazards, metrics tailored to human health concerns – such as heat index and wet bulb globe temperature – are more holistic assessments of extreme temperature events’ potential for heat-related illness and death. With heat waves projected to increase in duration and intensity in the future, understanding and effectively communicating heat hazards to the public and stakeholders becomes even more crucial. Contextualizing these events in real-time can serve as additional near-term risk guidance for stakeholders, allowing them to draw on previous experience to enact the appropriate level of heat intervention and deploy mitigating measures. Long used in hydrology for quantifying flood risk, intensity-duration-frequency (IDF) curves can be utilized similarly in temperature applications, providing the expected return period of an event given its intensity and duration.

By not imposing specific event definitions, IDF curves enable a single compact framework to inform a variety of human health applications, a few of which are highlighted in this presentation. We first demonstrate the construction of climatological IDF curves using an objective fitting algorithm applied to ASOS hourly observations (one of many potential options for input data). These climatological IDFs can then be combined with NWS forecasts and recent observational data within the framework to provide context for extreme events in real-time. Further distilling this product results in a tool with similar functionality for several stations simultaneously, covering scales from statewide to CONUS-wide, based on the needs of stakeholders. Potential customization of the IDF framework is subsequently demonstrated, including a focus on seasonal IDF curves, elevated overnight minimum temperatures, and applications beyond human health – exhibiting the far-reaching potential of this unified framework.