Extreme Heat Dome Builds Across U.S., Bringing Triple-Digit Temps and Health Risks

Credit: CNN Newsource

A powerful heat dome is settling over much of the U.S., bringing the hottest stretch of weather so far this year. The National Weather Service warns that dangerous, prolonged heat will grip the Plains, Midwest, Mid-Atlantic, and Northeast from Sunday through at least Thursday.

This “level 4-of-4” extreme heat risk will affect tens of millions, with temperatures expected to climb 15 degrees above normal. Forecast highs in major cities like New York, Washington, DC, and Boston could break daily records, with heat indexes reaching up to 110 degrees due to high humidity.

New York City could see highs near 97 degrees through early next week. Washington, DC may hit 100 degrees, while Boston is forecast to reach the mid-90s. Over 250 daily temperature records could fall on Monday and Tuesday alone, according to meteorologists.

Compounding the danger are warm overnight temperatures, which are rising faster than daytime highs due to climate change. Without nighttime cooling, the human body struggles to recover—especially those without air conditioning or access to cool environments.

Heat remains the deadliest form of extreme weather in the U.S., contributing to more than 800 deaths annually on average, according to a 2023 study. Emergency room visits spike during major heat events, particularly when high humidity and stagnant nighttime air prevent proper cooling.

This latest heat wave comes just as summer officially begins. The summer solstice occurred Friday night at 10:42 p.m. ET, marking the longest day of the year in the Northern Hemisphere and the official start of astronomical summer. Meteorologists, however, consider June 1 the start of summer for tracking seasonal weather patterns.

Though this particular heatwave may ease by the end of next week, it could be just the beginning of an intense summer. July and August are typically the hottest months across most of the country.

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