Millions of Americans are being warned not to leave children or pets in cars as temperatures reach "lethal" levels in New Jersey, Pennsylvania and Delaware.
The heat advisories issued by the National Weather Service (NWS) are in effect in parts of these states through the weekend. The advisories list several counties across New Jersey and Pennsylvania, as well as the Delaware city of Wilmington.
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"Do not leave young children and pets in unattended vehicles. Car interiors will reach lethal temperatures in a matter of minutes," the NWS advisories say.
A heat advisory is in place in some areas until 6 a.m. ET Saturday and until 6 a.m. ET Sunday in others.
Heat index values will reach highs of 99 to 102 degrees. They indicate how hot it feels to the human body when relative humidity is factored into the air temperature.
The advisories will then turn into excessive heat watches through Sunday evening. They warn of "dangerously hot conditions" with possible heat index values of up to 105 to 107 degrees.
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Heat advisories were also issued in parts of New York state and Ohio until 8 p.m. ET Saturday.
This week, heat waves swept over large parts of the U.S., causing record temperatures in some areas. The NWS told Newsweek that the "heat wave will continue over the next several days, with the most intense heat gradually shifting to different regions."
The heat wave in the Ohio Valley and Midwest will likely peak on Friday and Saturday, the NWS said. A heat wave in the mid-Atlantic and I-95 urban corridor from Washington, D.C., to New York City will likely peak over the weekend.
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In the Southeast, mid-South and Great Plains states, the heat wave is expected to peak early next week.
"This is a deadly event," New York Governor Kathy Hochul said."We have seen blizzards, we have seen flooding, we had hurricanes, we had tornadoes. But this heat event is most likely to cause more deaths."
People in all states where there are heat advisories or watches are advised to drink plenty of fluids, stay in an air-conditioned building, remain out of the sun and check up on relatives and neighbors.
The NWS also advises people to wear lightweight and loose-fitting clothing and limit strenuous activities to the early morning or evening hours if possible.
"Heat related illnesses increase significantly during extreme heat and high humidity events," the NWS warns.
