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Climate change

Find out what type of heat wave you’re really in for with NOAA’s HeatRisk dashboard

There’s more to assessing heat risk than looking at the temperature alone.

The HeatRisk Map (Screenshot/NOAA)

It’s time to prepare for another hot summer.

Last summer was the hottest on record, as climate change causes heat waves that are more frequent and last longer, according to the National Oceanic and Atmospheric Administration (NOAA). The best way to stay safe in high heat is to be ready for it in advance — which is why, in April, the NOAA expanded the availability of its HeatRisk tool to the entire contiguous United States.

HeatRisk was first launched in California in 2013 and expanded into other western states in 2017. It’s a collaboration with the Centers for Disease Control and Prevention shows heat impacts — not just temperature — across the country from the present to seven days ahead. 

“Heat can impact our health, but heat-related illness and death are preventable,” said CDC Director Mandy Cohen in April. “We are releasing new heat and health tools and guidance to help people take simple steps to stay safe in the heat.”

Beyond just temperature, HeatRisk shows how communities react to heat levels

At first glance, HeatRisk looks like any weather map with colors representing different weather conditions. The tool is a searchable map of the US that by default displays the current heat risks by color. Light green means little to no heat risk, yellow means minor heat risk, orange means moderate, red means major and magenta means extreme heat levels. 

The difference is that HeatRisk uses both temperature data from the National Weather Service (NWS) and several other parameters to determine risk, such as historic temperatures, previous climate trends and duration of high temperatures. 

For example, 90°F in August is a common temperature in the Southeastern US, and people who live there have acclimated to the heat by late summer. By contrast, if it’s June and it usually averages in the high 70s, so 90°F could be extreme and dangerous heat. 

Think of the current UK heat wave of 26°C, or 79°F, a temperature few in the US would call a heat wave. But when all things like average temperatures in June and the rarity of air conditioning are taken into consideration, it counts. 

Other factors, such as the night temperature, also indicate an extreme heat wave. If the temperature doesn’t dip at night, offering relief from high temperatures, it’s more risky than if it cools off at night. 

This is why in Philadelphia, for example, one day this week with an expected high of 97°F falls under major risk. Three days later, a 95°F day that follows two 100°F days with little overnight relief is an extreme risk. 

Weather map displaying hazardous weather conditions in Philadelphia area with heat advisory and excessive heat watch. The NWS forecast shows high temperatures throughout the week. Updated June 17, 2024.

Philadelphia on the HeatRisk map (

Use HeatRisk to know what to expect in your community

The tool is designed to be used by state and local governments, healthcare organizations, nonprofits, employers and regular people. 

It’s easy to use: Click on the magnifying glass to search for a location, and you’ll see a seven day color-coded heat forecast. You can click on each day for more information about the risks. The “Understanding Heat Risks” tab breaks down who is most at risk at different levels, and what you should do if you fall into an at-risk group.

The magenta extreme risk area is considered risky for the entire population for multiple days, especially those without access to an indoor air conditioned space. Power outages are also possible due to high electrical demands for cooling. 

People in magenta areas should stay indoors in air conditioning as much as possible, stay hydrated. Check on neighbors and at-risk members of the community such people who are of an advanced age, low income and/or homeless. 

People who work outdoors should take the day off or otherwise make accommodations to avoid the heat. Outdoor activities may be canceled.

NOAA stresses that heat affects different people, and different economic sectors, differently. Other things that can impact how heat impacts you are health conditions, medications, and whether you are new to the area from a cooler climate.

HeatRisk is still experimental, and the NWS is accepting feedback from the public through September 30.

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