'Scorching Summer 2023: Analyzing Extreme Heat in Southeastern Louisiana'

Summer 2023 saw unprecedented heat across southeastern Louisiana, including the Baton Rouge and New Orleans metropolitan areas. The local National Weather Service (NWS) office issued an astounding 32 Excessive Heat Warnings and 28 Heat Advisories from June 1 to August 31. This broke the previous record of 5 Excessive Heat Warning issuances in 2010 and 27 Heat Advisories in 2021 over the same time period. Every automated station in the New Orleans forecast area either broke or tied their previous record for warmest summer temperatures. Heat is the number one weather-related killer across the United States, and the NWS uses Heat Index and Wet Bulb Globe Temperature Index to determine the risk of excessive heat. New for 2024 is the HeatRisk tool, intended to show heat-related impacts in a climatological context with Centers for Disease Control and Prevention heat-health information. This study will address two key questions: (1) How would the new HeatRisk tool have performed during the extreme heat outbreak of 2023? (2) Do other heat tools/parameters that measure excessive heat and excessive heat risk correlate well with HeatRisk?

A detailed analysis of how HeatRisk performs in the New Orleans forecast area was conducted utilizing the historic HeatRisk tool available from the Weather Prediction Center, archived heat product issuances from NWS New Orleans, and heat-related emergency department visits in Louisiana Department of Health (LDH) Regions 1 (Southeast Parishes Region) and 2 (Capital Parishes Region).. An analysis of extreme HeatRisk days compared to heat product issuance in the NWS New Orleans parish/county warning area showed a high degree of correlation at 95.2% in the summer of 2023. Assessing heat-related illness and emergency department visit data from LDH in relation to Extreme HeatRisk days revealed that 64.5% of all heat-related emergency department visits in Louisiana Health Regions 1 and 2 occurred during Extreme HeatRisk days. This indicates a strong correlation between Extreme HeatRisk days and heat illness in Southeast Louisiana. Given the high correlation between Extreme HeatRisk days and Heat Index-driven NWS heat product issuances in the summer of 2023, a direct correlation can be made between heat index values exceeding 108°F and heat-related emergency department visits.

Based on the high correlation between HeatRisk, heat product issuances, and heat-related illnesses in the New Orleans forecast area, our conclusion is that the HeatRisk tool is a valuable addition to NWS operations. HeatRisk performed well during extreme heat outbreaks and provides a user-friendly way for partners, including the New Orleans Health Department, to communicate the risk of excessive heat effectively in their messaging and planning.