HeatRisk: The Intersection of Heat Forecasts and Health

Each year, extreme heat exposure leads to numerous deaths and illnesses. As climate change intensifies, extreme heat events are becoming more frequent, severe, and prolonged. Issuing alerts and health advisories before or during periods of extreme heat can save lives. These services are supported by weather and health agencies involved in emergency preparedness. Early warning systems and action plans have been shown to reduce risks of heat exposure. However, guidance on preventing health problems from heat exposure should be based on local epidemiologic evidence, which is often not available.

The Centers for Disease Control and Prevention (CDC) and the National Weather Service (NWS) have collaborated to identify temperature thresholds and develop a service that issues heat forecasts using data and methods relevant from a public health perspective. Each year, hot weather results in an average of over 1,220 deaths for which heat is listed as the underlying or a contributing cause on death certificates. However, these estimates might not capture the full spectrum of heat–related deaths, especially if excessive heat is not explicitly documented in death records. The CDC and NWS employed a nationally consistent study design and a modeling framework to link heat exposure with all-cause mortality data, determining heat-attributable deaths across locations with diverse climates.

The National Weather Service integrated health-based temperature thresholds provided by the CDC with local temperature parameters to devise experimental HeatRisk — a numeric and color-coded alert system. HeatRisk is the first multi-tiered framework that applies a consistent approach across different climate regions, incorporates high-resolution climatology and locally-relevant health evidence, and provides decision makers with an easy-to-use, public heat-appropriate heat service. This new system highlights the importance of collaborating with multiple stakeholders and across multiple disciplines. It can complement existing information systems by offering consistent prevention messages for heat through better coordination between weather and public health agencies at various geographic levels before, during, and after extreme heat events.