A dangerous heat wave will grip much of the nation through the Independence Day weekend, with temperatures reaching as high as 105 degrees in some areas and more than 145 million Americans under heat warnings or watches as of Tuesday morning.
The National Weather Service estimates that extreme heat warnings currently affect more than 102 million people nationwide, with another 43 million under extreme heat watches. The affected region spans a broad swath of the Midwest, Ohio Valley, and Northeast, including Illinois, Indiana, Ohio, Missouri, Iowa, Wisconsin, Michigan, Kentucky, parts of Minnesota, Kansas, Tennessee, and Pennsylvania. New Jersey, southern New England, downstate New York including New York City, and potentially the Washington, D.C.–Baltimore area are also in the warning zone.
The extreme temperatures stem from a heat dome—an area of high pressure that acts like a lid, trapping hot air beneath it and preventing cooler conditions from moving in.
Peak Heat Expected Thursday and Friday
"We're looking at temperatures generally 100 to 105" for Thursday, July 2, and Friday, July 3, as the heat wave peaks, National Weather Service meteorologist Joe Wegman told NPR. The mid-Atlantic region will experience temperatures 10 degrees to 15 degrees above normal for this time of year.
"On the East Coast, for sure. We're expecting record-breaking temperatures," Wegman told NPR. He noted that on the actual Fourth of July—Saturday, July 4—temperatures will come down slightly from their peak levels.
Humidity will compound the danger, producing heat indices of 105 to 115 degrees in parts of the Midwest and Mississippi Valley through Thursday and for the Mid-Atlantic and Ohio regions in the following days. According to the National Weather Service, the combination of warm overnight lows—generally remaining in the 70s—will provide limited relief, creating "an increased risk of heat-related illnesses, especially for vulnerable populations and those without adequate cooling."
Health Risks Affect All Age Groups
While the extreme temperatures pose particular threats to older individuals, those with respiratory problems, and pets, Wegman emphasized that "it's the kind of heat that affects everyone of all ages and health conditions," according to NPR.
Health officials recommend staying indoors whenever possible, maintaining proper hydration, and taking frequent breaks from any physical exertion. The heat wave has already forced summer camps and other outdoor activities in the Midwest to be canceled, according to The Associated Press. Communities across affected regions have opened cooling centers and are urging residents to take precautions.
Climate Change Connection
Climate change, caused primarily by burning fossil fuels, is making heat waves hotter and more prolonged than in the past. The average number of heat waves in the United States has doubled since the 1980s.
"What we're seeing ... is exactly the kind of thing that we can expect going forward," Ashley Ward, director of the Heat Policy Innovation Hub at Duke University's Nicholas Institute, told NPR. "The baseline is warmer. So, when a heat dome or a high-pressure system sets up, it's now starting from a hotter floor. And so that makes the extreme heat more likely."
As the nation prepares for Independence Day celebrations, residents in affected areas should monitor local forecasts, heed heat warnings, and adjust outdoor plans accordingly to protect themselves and their families from the dangerous conditions.
