More Than 165 Million Americans Under Heat Alerts as High Temperatures Hit Much of US

The heat is expected to last until the middle of the week, according to forecasters.

Tourists walk along the National Mall near the Lincoln Memorial in Washington as a heat dome sits over the region leading to extremely high temperatures on July 25, 2025. Saul Loeb/AFP via Getty Images

More than 165 million people in the United States were under some form of heat advisory or warning as soaring temperatures are expected for much of the East Coast, South, and Midwest starting Monday and lasting until the middle of this week.

A tracker run by the federal government shows that roughly 168 million people are under heat alerts across the United States as of Monday afternoon.

“Extreme heat warnings” were issued for sections of Iowa, Nebraska, South Dakota, Missouri, Kansas, Tennessee, Illinois, Arkansas, Mississippi, Louisiana, North and South Carolina, Georgia, Florida, Ohio, West Virginia, and Kentucky.

Cities under those warnings include St. Louis, Missouri; Memphis, Tennessee; Raleigh, North Carolina; Sioux Falls, South Dakota; and Des Moines, Iowa, among others.

Various heat watches and advisories were issued across most of the East Coast and Midwest, including cities like New York City, Detroit, Milwaukee, Chicago, Boston, Pittsburgh, Cleveland, and Philadelphia, according to the map, which is updated by the National Weather Service (NWS).

In a forecast update on Monday, the NWS said that “extreme heat is expected to continue across much of the Southeast and this week, with the most dangerous combination of high temperatures and humidity occurring through Wednesday.”

Heat levels could be dangerous to people without proper hydration or cooling, it said, as some areas will see “heat index” values surpassing 110 degrees to 115 degrees Fahrenheit due to the humidity.

“Drink plenty of fluids, stay in an air-conditioned room, stay out of the sun, and check up on relatives and neighbors,” the weather service said in an advisory over the weekend. “Take extra precautions when outside. Wear lightweight and loose fitting clothing. Try to limit strenuous activities to early morning or evening. Take action when you see symptoms of heat exhaustion and heat stroke. Stay cool, stay hydrated, stay informed.”

Health officials have said that people at the most risk of heat stroke or heat exhaustion include infants, younger children, older adults, people with mental health problems, pregnant women, and those with chronic medical conditions such as heart disease, obesity, and poor blood circulation.

Symptoms of heat stroke include a body temperature of 103 degrees or higher; red, hot, dry, or damp skin; a rapid and strong pulse; nausea, confusion; dizziness; headache; or a loss of consciousness, according to the U.S. Centers for Disease Control and Prevention and other health agencies.

People suffering from heat stroke should receive immediate medical attention, and 911 should be called, officials say.

Also Monday, the NWS warned that thunderstorms in South Dakota may develop into a derecho, or a straight-line wind storm that can cause damage, by Monday evening. The storm system is expected to hit parts of southern Minnesota and northern Iowa, while wind gusts are expected to exceed 75 mph in some cases, the agency advised.

Several tornadoes and hail are also possible during the derecho, according to the NWS. Heavy rains over parts of the northern Plains states and upper Midwest region could also trigger flash flooding, it added.

The Associated Press contributed to this report.