Temperatures as high as 105 F are forecast for the Atlantic Coast : NPR

A significant heat wave is expected to set new temperature records across the Midwest and parts of the East in the coming days, with temperatures potentially reaching up to 105 degrees as the July Fourth weekend approaches, according to forecasts.

The National Weather Service (NWS) reported on Tuesday morning that over 102 million people nationwide are currently under extreme heat warnings, with an additional 43 million facing extreme heat watches. The affected regions span a large section of the Midwest, Ohio Valley, and Northeast, including states such as 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 impacted, as per the NWS.

The heat wave is attributed to a heat dome, a high-pressure area that traps hot air like a lid. According to Joe Wegman, a meteorologist with the NWS, temperatures are expected to reach between 100 and 105 degrees on Thursday and Friday, at the peak of the heat wave. The mid-Atlantic region is anticipated to experience temperatures 10 to 15 degrees above normal.

“On the East Coast, for sure. We’re expecting record-breaking temperatures,” Wegman said.

The extreme heat poses significant risks, particularly for older individuals, those with respiratory conditions, and pets. “It’s the kind of heat that affects everyone of all ages and health conditions,” Wegman emphasized. He noted that temperatures would slightly decrease by Saturday, the actual Fourth of July.

For safety, it is advisable for people to stay indoors as much as possible, remain well-hydrated, and take frequent breaks from physical activity.

Humidity is expected to create heat indices of 105 to 115 degrees in the Midwest and Mississippi Valley through Thursday, and in the Mid-Atlantic and Ohio regions in the following days. With warm overnight lows generally remaining in the 70s, relief will be limited, and the prolonged heat increases the risk of heat-related illnesses, especially for vulnerable groups and those without adequate cooling, according to the NWS.

The heat wave has already led to the cancellation of summer camps and other outdoor activities in the Midwest, reported The Associated Press. On Monday, as millions across the Midwest endured the heat wave expected to spread eastward, communities opened cooling centers and urged residents to stay hydrated and avoid strenuous activities.

Climate change, primarily driven by fossil fuel combustion, is intensifying and prolonging heat waves compared to the past, with the average number of heat waves in the U.S. doubling since the 1980s.

“What we’re seeing … is exactly the kind of thing that we can expect going forward,” said Ashley Ward, director of the Heat Policy Innovation Hub at Duke University’s Nicholas Institute.

“The baseline is warmer,” Ward explained. “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.”