HeatRisk and the Evolution of Heat-Related Services at NOAA/NWS Phoenix

Historically, the perception of heat being a significant threat to the local population’s health in Phoenix, Arizona, was often either one of dismissal or a defeated acceptance. It is now widely recognized that heat is the deadliest weather phenomenon not just in Arizona but across the United States. According to the Centers for Disease Control and Prevention, nearly 700 people die every year due to heat-related or heat-caused illness. In Maricopa County, Arizona, alone, where much of the Phoenix metropolitan area resides, heat-related or heat-caused deaths reached 155 in 2017 according to the Maricopa County Public Health. While these numbers are striking, they represent a significant change in perceptions and attitudes in the local weather and health community. Today, heat is treated as a serious threat. Forecasters at the NOAA/National Weather Service (NWS) aggressive forecast and message significant heat events and proactively work closely with partners in the health and emergency response communities to mitigate impacts. This approach by NWS forecast offices across Arizona, and more broadly the West, is a major evolution from just ten years ago. Local warning criteria for Excessive Heat Warnings in Phoenix were, prior to 2006, set so high as to essentially be unattainable. This was fairly typical in areas where extreme heat was viewed as the climatological norm. Only after a particularly intense year (2005) with numerous heat deaths did this view begin to change. Over the next several years, the NWS Phoenix office adjusted its warning criteria and forged improved ties with partners to better serve its constituents. This effort, which gradually involved several other NWS offices in the region, eventually developed into the NOAA/NWS HeatRisk project. This presentation will provide the local NWS Phoenix perspective on the evolution of its local heat program, the development of the HeatRisk project, current applications and successes of HeatRisk, and future plans for expansion across the continental United States.