Massive 'heat dome' is bringing 'extremely dangerous' temperatures to the eastern half of the US

A major heat wave is set to scorch the central and eastern U.S., with millions of Americans facing potentially record-breaking extreme heat.

Temperatures and humidity will rise as much of the country finds itself under a "heat dome," The Associated Press reported. A heat dome occurs when an area of high pressure in the atmosphere traps warm air beneath, effectively like placing a lid on top of a pot.

The National Weather Service (NWS) has warned that "extremely dangerous" levels of heat are likely over the weekend and into next week, as sunny days, light winds and a lack of overnight cooling worsen high temperatures.

"Heat is likely to reach dangerous levels over much of the Central and Eastern U.S.," an NWS representative wrote in a weather update posted on Facebook. "Particular concern exists for the Ohio, Valley, Eastern Great Lakes, Interior South, and much of the East Coast, where the heat will be more persistent."

Meteorologists predict that the heat wave will hit the central U.S. between Friday (June 20) and Sunday (June 22), before making its way to the East Coast next week.

Temperatures are expected to reach nearly 100 degrees Fahrenheit (38 degrees Celsius) across the central and eastern U.S. (exceeding 100 F in some areas). Affected cities such as Denver, Washington, D.C., and New York City will experience several consecutive days of heat, weather website AccuWeather reported in a forecast.

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"The magnitude and longevity of this heat wave will be a shock to the system," AccuWeather senior meteorologist Chad Merrill said in the forecast.

Moist ground will absorb some of the sun's energy, preventing temperatures from exceeding 100 F over much of the affected area. However, the heat will also evaporate this moisture, adding to what are already expected to be humid conditions, according to AccuWeather.

The NWS warned the anticipated levels of heat can be dangerous to anyone who doesn't have effective cooling systems or adequate hydration, and is especially risky to people taking part in lengthy outdoor activities.

Our warming world

Heat waves are becoming more frequent and intense with climate change. That doesn't necessarily mean climate change is responsible for the latest heat wave, but scientists have long predicted that there will be more of these kinds of extreme weather events as the planet warms.

Last year was the hottest year for global temperatures since records began, while 2025 has already been marked by a string of record-breaking or near-record-breaking warm months.