CHICAGO — A dangerous heat wave intensified across the central and eastern United States on Tuesday, with more than 74 million people under heat alerts as a strengthening dome of high pressure pushed temperatures into the triple digits, the National Weather Service said.
The agency warned that "dangerous to record setting heat" would expand across the eastern two-thirds of the country in the coming days, with heat index values, which factor in humidity, reaching 100 to 110 degrees Fahrenheit (38 to 43 Celsius) and as high as 115 F (46 C) in some areas by midweek.
Extreme heat warnings were in effect Tuesday for parts of Iowa, Missouri and Kansas, while watches and advisories stretched across the Central Plains, Midwest, South and Northeast, according to the weather service. Major cities including Chicago, Detroit, St. Louis, Dallas and Nashville were forecast to see some of their highest temperatures of the year so far.
By later this week, more than 175 million people in the Midwest and East are projected to face "major" or "extreme" heat-related health risk, according to the weather service's experimental HeatRisk index. Forecasters said the heat dome was expected to peak around July 3 and 4, coinciding with the Independence Day holiday weekend, with some areas of the mid-Atlantic potentially approaching all-time temperature records.
The Centers for Disease Control and Prevention urged residents to limit outdoor activity, stay hydrated and seek air-conditioned spaces, warning that the combination of heat and humidity poses a risk of heat exhaustion and heat stroke even for healthy adults.
No heat-related deaths had been officially confirmed in connection with the current event as of Tuesday. The weather service said the heat was expected to persist into the holiday weekend before gradually shifting westward, with conditions continuing to be monitored.
