Heat Dome Traps More Than Half of the U.S. Through Fourth of July Weekend

A dangerous heat wave under a heat dome is expected to trap more than half of the United States through the holiday weekend, with forecasters warning that “more than 300 records are expected to be set by Saturday.”

“- Published Millions of people across the US East Coast are enduring dangerous heat and humidity, with temperatures expected to reach and stay at 38C (100F) for several days”

BBC

In New York City, Mayor Zohran Mamdani warned that “These are extremely dangerous conditions,” as an extreme heat warning is in effect in the city until 9 p.m. ET on Saturday.

BBC

The National Weather Service warned that temperatures between 95F (35C) and 105F (40.5C), combined with high humidity, will push heat index values across parts of the region to between 100F and 115F.

The Weather Channel said over 165 million Americans in the Midwest and East will be at risk of either “major” or “extreme” heat-related health issues, with triple-digit heat indices expected for many areas.

CBS News meteorologist Nikki Nolan said temperatures will be 20 to 30 degrees above average as the heat wave intensifies in the Midwest to the East Coast.

New York City is deploying vans staffed with nurses and paramedics, and Mamdani told residents, “My recommendation to all New Yorkers is to stay inside and stay cool.”

The Guardian reported that Mamdani urged residents to “Plan for extreme temperatures. Drink more water than usual,” and it said the city’s cooling vans are set to provide wellness checks, medical care, water and other supplies such as electrolytes and sunscreen.

CBS News

In Washington, D.C., the National Weather Service issued an extreme heat watch for Thursday and Friday with forecast highs of 103, and an extreme heat warning is in effect until 8 p.m. Saturday.

The Guardian said Muriel Bowser urged residents to “Consider the heat as you make plans for the Fourth of July and America250,” while advising people to avoid strenuous outdoor activity and limit time outdoors whenever possible.

Kathy Hochul said the state’s electric grid was under “heavy strain as this heatwave drives up energy demand,” and she encouraged New Yorkers to “voluntarily conserve power” by setting A/C between 75F-78F.

CBS News described heat as “the leading cause of weather-related deaths,” and it said heat exhaustion can include fatigue, light-headedness, muscle cramps and upset stomach.

“The WHO Director-General announces that the organization has formed a partnership with FIFA to protect players, staff, and fans from extreme heat during the 2026 World Cup”

Euronews

Dr. Catrina Cropano, the medical director of the emergency department at New York City's Mount Sinai West, said for heat stroke the differential factor is “altered mental status, that confusion,” adding that people should come into the emergency department as quickly as possible.

The Weather Channel said daily low temperatures won’t drop below the mid-80s for some, offering little relief at night, and it warned that life-threatening heat indices will climb above 100 degrees in many areas.

Zonebourse Suisse reported that the Secretary of Energy issued an emergency order for PJM Interconnection due to rising electricity demand and limited generating capacity, citing forecasts of high temperatures reaching or exceeding 35°C (95°F).

It added that PJM projects peak loads of about 159,563 MW on July 1, 2026, and about 162,860 MW on July 2, 2026, increasing the risk of a supply shortfall that could jeopardize its ability to meet electricity demand.