Millions of Americans Warned of ‘Dangerous, Life-Threatening’ Conditions

AccuWeather meteorologists are warning of “dangerous, life-threatening” conditions for millions of Americans as a heat wave is moving across large portions of the U.S. later this week, with temperatures expected to top 100 degrees Fahrenheit across several states.

Millions of Americans are expected to face major or extreme heat risks in the coming days, with the National Weather Service projecting over 152 million affected on June 23.

Why It Matters

Extreme heat is the deadliest weather hazard in the United States, posing serious health risks nationwide. Over 200 people died of heat-related illnesses in the U.S. last year. Since 1979, more than 14,000 Americans have died from heat-related causes, according to the Environmental Protection Agency.

A “heat dome” is moving through the U.S., later this week, with millions of Americans across a range of large cities to be impacted. Several extreme heat warnings and heat advisories have been issued across cities and states.

The heat wave coincides with the longest days of the year, with Friday marking the summer solstice.

What To Know

“The highest temperatures so far this year will combine with increasing humidity and intense summer sunshine to create dangerous, life-threatening conditions for roughly 170 million people,” AccuWeather meteorologists said about the upcoming heat wave.

The NWS predicts that on June 21, 62.5 million will be under major or extreme heat risk, 141 million on June 22, 152 million on June 23, 144 million on June 24 and 105 million by June 25.

The NWS Weather Prediction Center similarly warned that “extremely dangerous levels of heat” are likely over the Central and Eastern U.S. These levels “may exacerbate the heat health impacts, especially by midweek,” a June 20 message from the center said.

Areas of particular concern include the Ohio Valley, eastern Great Lakes, interior South and much of the East Coast, according to a warning from the NWS. In addition to record-high temperatures, those regions are expected to “lack overnight cooling,” which will “significantly increase the danger.”

Heat index values—how the temperature feels to the body when humidity is factored in—were expected to reach triple digits in some areas that have Extreme Heat Warning issued by the NWS.

Large U.S. cities have begun issuing warnings to residents ahead of the heat wave. In Annapolis, Maryland, officials posted an alert on the city’s website and announced the activation of cooling centers “to provide temporary relief from extreme heat conditions and help prevent heat-related illnesses,” as temperatures are expected to exceed 100 degrees and may reach 110.

What People Are Saying

AccuWeather Chief Meteorologist Jonathan Porter said: “Extreme heat is tragically the leading cause of weather-related fatalities in America. There is an amplified risk of heat-related illnesses because this is the first heat wave of the year for millions of people, and their bodies are not yet acclimated to this type of heat and humidity.”

Ben Noll, a meteorologist for The Washington Post, said on X, Wednesday: “A heat dome will form over central states on Friday before expanding and intensifying. Heat domes are large and strong heat-trapping lids of high atmospheric pressure. This one will last around a week, with numerous temperature records expected to fall.”

AccuWeather Chief On-Air Meteorologist Bernie Rayno said: “It will be exceptionally warm at night with little relief once the sun goes down. Many urban areas may struggle to drop below 80 at night, and that can take a toll on the body without air conditioning.”

Kevin J. Simmons, Director of the City of Annapolis Office of Emergency Management said in a Friday statement: “Heat waves like this one pose a serious risk, especially for our most vulnerable neighbors. We are asking all residents to take this heat seriously. Check on your neighbors, stay hydrated, limit outdoor activity, and know where to go if you need to cool down. Our goal is to keep everyone safe and informed throughout this dangerous weather event.”

National Weather Service wrote in an X, formerly Twitter, post on Wednesday: “Triple-digit heat indices will be common through next week, with oppressive humidity. Record-breaking heat will be dangerous to those working and playing outdoors so take precautions.”

What Happens Next

The NWS warns, “This level of heat can be hazardous to anyone without effective cooling and/or adequate hydration, especially those engaging in lengthy outdoor activities.”