It's got so Sizzling that the U.S. government has added a new color at the top of its Heat scale

What’s hotter than red-hot? Magenta-hot.

Yes, that’s the color used in a new online heat warning system that National Weather Service (NWS) and the Centers for Disease Control and Prevention (CDC) have introduced that that combines meteorological and medical risk factors with a seven-day forecast.

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“For the first time we’ll be able to know how hot is too hot for health and not just for today but for coming weeks,” Dr. Ari Bernstein, director of the National Center for Environmental Health, said at a joint news conference by government health and weather agencies.

Magenta is the worst of five heat threat categories, hitting everybody with what the agencies are calling “rare and/or long-duration extreme heat with little to no overnight relief.” Below that is former chart-topper red, considered a major risk, which hurts anyone without adequate cooling and hydration. Red is used when a day falls within the top 5% hottest in a particular location for a particular date; when other factors come into play, the alert level may bump even higher to magenta, weather service officials said.

And from the bottom of the scale, pale green is little to no risk. Yellow is minor risk, mostly to the very young, old, sick and pregnant. Orange is moderate risk, mostly hurting people who are sensitive to heat, especially those without cooling, such as the homeless.

“Heat is a threat to our health,” CDC Director Dr. Mandy Cohen said. She said last year more than 120,000 people were taken to the emergency room in the United States because of heat. Last year, the hottest on record globally, was one of the deadliest in decades for heat, according to government records.

Searing temperatures are by far the biggest weather cause of death in the United States, said National Oceanic and Atmospheric Administration chief Rick Spinrad, citing CDC data of 1,200 deaths per year.

Both the weather service and CDC will put versions of the tool on their websites. Enter a ZIP code on the CDC dashboard to get more focus on health risks and air quality and zoom in on the weather service map online for more detailed forecasts and explanations. Both versions include heat risk for the next seven days and there is a Spanish edition. The CDC site is https://www.cdc.gov/heatrisk and the weather service version is https://www.wpc.ncep.noaa.gov/heatrisk/