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Heat Wave to Affect More Than 200 Million in U.S. Through July 4
A heat wave driven by a heat dome is affecting more than 200 million people across large parts of the United States this week. The National Weather Service forecasts extreme temperatures and high humidity persisting through the Fourth of July holiday.
Jun 30, 11:01 AM·2m read5 sources
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A heat wave is affecting more than 200 million people across large parts of the United States this week and is forecast to persist through July 4. The National Weather Service said a heat dome will bring several days of extreme temperatures, high humidity, and intense sunshine to much of the Midwest, Mississippi Valley, Ohio Valley, and East Coast around the Fourth of July.
Widespread major to extreme HeatRisk is forecast from Tuesday through Thursday across the Midwest and Mississippi Valley before spreading eastward later in the week.
High temperatures in the 90s to low 100s combined with humidity are expected to push heat-index values between 100 and 110 degrees, with some areas reaching 115. Level 4 Extreme HeatRisk is forecast from Thursday through Saturday across parts of Michigan, Wisconsin, Illinois, Indiana, Ohio, Iowa, Missouri, Tennessee, Kentucky, West Virginia, North Carolina, Virginia, Pennsylvania, and New York.
The National Weather Service said dozens of record highs are expected to be broken across much of the Northeast during that period.
An NWS map showed the most intense heat concentrated across the Mid-Atlantic and central Appalachians on July 4, surrounded by major heat risk across the eastern half of the country. AccuWeather chief meteorologist Jonathan Porter said heat domes have become more intense over the last 10 years and often break records.
A heat dome traps hot air over a region for a week or longer, limiting cloud formation, rainfall, and thunderstorms while allowing steady sunshine.
The pattern also causes rapid ground-moisture loss, raises drought risk, and allows pollutants to accumulate, reducing air quality in urban areas. In contrast, a heat wave is a shorter stretch of unusually high temperatures lasting three or more consecutive days.
The National Weather Service urged residents to stay hydrated, limit outdoor time during peak heat, wear lightweight clothing, take breaks in air-conditioned spaces, and check on vulnerable neighbors.
