(Bloomberg) -- As the US prepares for another summer of potentially record-breaking heat, the Biden administration on Monday unveiled a new tool to help Americans anticipate high temperatures and their potential impact on human health. Dubbed HeatRisk, and now available online, the tool combines National Weather Service temperature forecasts with heat-related health data from the Centers for Disease Control and Prevention to provide and map a seven-day forecast of possible heat risks across the US. 

“Millions of Americans are impacted by extreme heat waves, which are growing in intensity, frequency, and duration due to climate change,” said Don Graves, US Deputy Secretary of Commerce, at a Washington, DC press conference announcing HeatRisk. “Last summer, we saw record temperatures across the country, a trend that’s likely to continue in the months ahead.”

The crux of the tool is what’s called an “experimental color-numeric-based index,” according to the NWS. It takes into account how unusual the heat is for that time of year and the duration of heat during the day and at night to forecast whether anticipated temperatures pose an increased health risk. A 0 (or light green) on the index reflects little to no heat risk, while a maximum reading of 4 (magenta) reflects extreme risk of long-duration heat with little to no overnight relief.

Now rolling out nationwide, a version of the HeatRisk tool has been used by some states since 2014. Arizona’s Maricopa County uses it to inform hazard-mitigation planning, while schools in California’s Sacramento area use it for decisions about outdoor activities. The tool is also used by the California Governor’s Office of Emergency Services and by health partners in Orange County, California, according to Richard Spinrad, who leads the National Oceanic and Atmospheric Administration, under which the NWS sits. 

“The bottom line is HeatRisk will help people understand what forecast heat means for them and their families,” Spinrad said at the press conference. 

As greenhouse gas emissions drive up global temperatures, extreme heat is costing billions of dollars in crop yields, energy prices and lost productivity. It’s also killing people. In the US, heat is the leading cause of weather deaths — ahead of hurricanes, floods and tornadoes — responsible for an estimated 1,200 fatalities each year. In 1995 in Chicago, an extreme heat wave killed over 700 people. In the Pacific Northwest in 2021, another heat wave resulted in some 600 excess deaths. 

“Heat is a threat to our health,” CDC director Mandy Cohen said at the press conference. “Heat can make underlying health conditions worse, and heat-related illness, like heat exhaustion and heat stroke, can cause serious illness and even lead to death. Heat can be especially dangerous for certain people, including very young kids, kids with asthma, older adults, pregnant moms and people with underlying health conditions like heart disease.” 

Cohen said that last year, heat-related illnesses caused more than 120,000 emergency room visits across the US. On Monday, the CDC announced its own new heat-related dashboard, which includes the NWS’ HeatRisk map as well as new guidance for clinicians and patients about how to prepare for high temperatures.

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