Extreme heat kills more than 600 people in the U.S. annually. The National Oceanic and Atmospheric Administration (NOAA) ranked heat as the top cause of weather-related fatalities in the nation in 2021. As heat waves intensify globally, the Adrienne Arsht-Rockefeller Foundation Resilience Center believes naming and ranking them on a 1 to 3 severity scale using health-based metrics could save lives. Unlike tropical storm categories based on the storm's intensity, each heat wave category level – Category 1, Category 2 and Category 3 – is based on thresholds for the expected rise in all-cause mortality for each location when temperatures rise. The World Meteorological Organization announced that it does not plan to rank or name heat waves. What’s been established for tropical cyclones may not necessarily translate to naming heat waves, the WMO said.