Hottest temperatures in over a decade threatened in parts of eastern US as dangerous heat dome expands and intensifies
By Meteorologists Briana Waxman, Chris Dolce
(CNN) — Half of all Americans are facing prolonged, dangerously hot temperatures from an intense heat dome as they head outdoors to celebrate the country’s 250th Independence Day.
The temperatures in some spots in the eastern US, like New York City and Washington, DC, could be the hottest in over a decade, and numerous high temperature records are likely to fall in the coming days.
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The oppressive heat and humidity are already gripping the Midwest and South and it will expand to the Mid-Atlantic and Northeast on Wednesday. The sprawling heat dome will then park over the East, particularly the Interstate 95 corridor, and peak by Friday.
Many areas will endure consecutive days of temperatures in the mid-90s to low 100s. Humidity will make it feel even hotter and make it harder to cool down — pushing “feels like” temperatures as high as 110 degrees or more.
Heat waves worldwide are becoming more harsh and frequent because of human-caused warming from fossil fuel pollution. The record-shattering heat waves in Europe last week and in the western US in March are two recent examples.
Heat is the deadliest type of weather in the US, with a higher annual average death toll than tornadoes, hurricanes and lightning combined, according to weather service statistics.
Why this heat wave is so dangerous
More than 180 million people are in a Level 3 of 4 “major” or Level 4 of 4 “extreme” heat risk across the eastern half of the US, according to the National Weather Service.
Emergency room visits for heat-related illness surge on “major” and “extreme” risk days, according to the National Weather Service.
It’s the temperatures and the humidity that increase the health risks. High humidity keeps temperatures elevated and prevents sweat from evaporating efficiently, making it harder for the body to cool itself.
The big concern isn’t just how hot afternoons will become, but also that the heat will be long-lasting and won’t stop when the sun goes down, giving anyone without proper cooling or hydration little-to-no time to properly cooldown.
Over 300 record warm overnight lows could be challenged through the weekend.
Low temperatures this week won’t fall below the lower-to-middle 70s from the Midwest and South to the East Coast. Urban areas, where concrete and asphalt absorb heat during the day and slowly release it overnight, could struggle to fall much below 80 degrees.
Where records could fall
Over 150 daily record highs could be tied or broken in dozens of locations between Tuesday and Saturday in addition to the record warm overnight lows. Charlotte, North Carolina, Cleveland, New York City, Pittsburgh and Washington, DC, are just some of the cities where records could fall.
Baltimore and Washington, DC, are forecast to come within a few degrees of their all-time record highs of 107 degrees and 106 degrees, respectively, on Friday. New York City has a shot at consecutive 100-degree days on Thursday and Friday for the first time since July 2011.
In eastern Virginia, the weather service says this could be the region’s most significant heat wave since July 2012, which resulted in a dozen deaths in the state, among the more than 30 heat-related fatalities across four states.
Richmond, Virginia, is forecast to top 100 degrees for three consecutive days, potentially breaking daily records each day.
In North Carolina, Raleigh could get within a few degrees of its all-time high temperature record of 106 degrees on Saturday.
Heat collides with July Fourth holiday
The heat wave is expected to peak during one of the busiest travel and outdoor celebration periods of the year. Millions of Americans attending parades, cookouts, sporting events and Fourth of July fireworks should prepare for dangerous heat, particularly during the afternoon and early evening hours.
Washington, DC, is prepping for a surge of visitors during events celebrating America’s 250th anniversary this week. And while marquee events like Friday’s “A Capitol Fourth” concert and Saturday’s fireworks display are being held at night, organizers are also touting daytime attractions like DC’s monuments, waterfronts and zoo.
Hydration will be available inside secure areas at Fourth of July events, DC Fire and EMS Chief John Donnelly said at a Monday news conference. There will also be first aid tents, response teams and extra ambulances in service, he added.
“We’re also doing the same thing out in the community,” Donnelly told reporters. “We’ve added resources in addition to the regular fire and EMS resources that are available throughout the city… We just need everybody to do their part, take their time, drink a lot of water and be safe out there.”
New York Mayor Zohran Mamdani has rolled out several heat awareness initiatives this month, including updating the city’s more than 2,000 LinkNYC kiosks to provide directions to cooling centers within a 10-minute walk.
In Nashville, crews will conduct “Heat Patrols” starting Monday afternoon to “check on vulnerable people including the unhoused,” and offer cold water and other resources, according to the city’s Office of Emergency Management.
Parts of the Midwest and Northeast will see temperatures ease later in the holiday weekend as the upper-level ridge of high pressure weakens and shifts westward, allowing thunderstorms to develop. But above-average temperatures are expected to persist across much of the South into the following week.
World Cup impact
Three outdoor matches during the Round of 32 will be impacted by heat.
Croatia and Portugal will face off Thursday evening at 7 p.m. ET in Toronto where hot and muggy conditions will make it feel like the upper 80s. Scattered thunderstorms are also possible.
Friday’s World Cup match at 6 p.m. ET in Miami could be the venue’s hottest one yet. Argentina and Cape Verde will kickoff with a temperature near 90 degrees and a heat index in the low 100s.
A match in Kansas City on Friday at 8:30 p.m. CT between Colombia and Ghana will avoid the hottest time of the day, but a heat index in the middle 90s is still expected at game time.
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CNN’s Matthew Rehbein, Devon Sayers and Kate S. Petersen contributed to this report.
