Assessing Spatial and Temporal Distributions of Extreme Heat for Impact-Based Heat Early Warning Systems in the Carolinas

Extreme heat is the primary cause of weather-related mortality in the United States. As global temperatures continue to climb due to climate change, extreme heat events (EHEs) are projected to increase in frequency. While EHEs undoubtedly imperil the integrity of infrastructure and agriculture, repeated exposure to EHEs can increase communities’ vulnerabilities to multifaceted heat-related issues, including health complications. Specifically, the Carolinas are especially susceptible to EHE occurrence and their related hazards due to mid-tropospheric ridging that contributes to warm air advection, light winds, increased humidity, and extended periods of high temperatures. Due to the unique topographic and demographic heterogeneity across the Carolinas, it is imperative to consider a localized assessment of extreme heat risk in both rural and urban areas. In order to identify the geographic variability and temporal occurrence of EHEs and in North and South Carolina, this study will originate a climatology of EHEs and identify localized hotspots of EHEs in both states. First, we examine the spatial and temporal distribution of extreme heat over the historical period to assess the frequency and relative severity of EHEs across the Carolinas. Daily maximum and minimum temperatures from 1981 to 2022 will be extracted from the Parameter-elevation Regressions on Independent Slopes Model (PRISM) provided by Oregon State University. Using specific maximum and minimum temperature thresholds, EHEs meeting such thresholds and their probabilities of exceedance will be analyzed. The spatial distribution of these EHEs will also be evaluated to reveal localized vulnerabilities of certain communities to extreme heat. In addition, the probabilities of both states experiencing EHEs over time will be calculated and visualized in order to heighten public awareness of EHE risks in a warming climate. To better understand the physiological impacts of EHEs and humidity in the contemporary climate of the Carolinas, daily maximum heat index (HI) values will be analyzed, with specific emphasis on previously established hotspots from 2002-2022. Historical trends of EHEs in these hotspots will help identify targeted regions of future heat mitigation and preparedness strategies. Future work will integrate heat-related emergency department (ED) data from North Carolina and South Carolina in order to identify societal impacts of extreme heat.