US heat wave persists with tens of millions still under warnings
At least 40 million people across the central and southern United States faced extreme heat warnings for a second consecutive day Sunday as a heat dome continued to drive temperatures to dangerous levels.
Sweltering heat and oppressive humidity gripped large portions of the United States for another day on Sunday, with the National Weather Service reporting heat indexes well above 100°F (38°C) from Minnesota to Mississippi and extending into Southern California and Nevada. Parts of the Southwest were expected to reach highs of 120°F (49°C).
Meteorologists attributed the scorching conditions to a heat dome, a meteorological phenomenon where high pressure traps warm air, intensifying and prolonging hot weather. "It's extraordinarily hot," said Pete Miller, an outreach manager for the homeless services network Threshold CoC, which was distributing water in Omaha, Nebraska. "We're seeing a lot of people who are exhausted, drained by the heat in a way that is really dangerous. The humidity is insane. You stand outside for 30 seconds and you get drenched. And it's going to be like that all night."
Rapid City, South Dakota, set an all-time high of 112°F (44°C) on Saturday. A horse race at Canterbury Park in Shakopee, Minnesota, was canceled Sunday due to the heat. NWS meteorologist Bob Oravec noted the heat was "affecting a lot of people right in the middle of the country" and said the core of the heat would shift southward by early next week.
The moist air also fueled the risk of severe thunderstorms, flash flooding, and hail around the Great Lakes on Sunday, with the potential for heavy storms moving east in the coming days. "If you have a heat dome in one part of the country, you'll have a different corresponding weather in another part," Oravec said. "It's all related."
Temporary relief is expected in the central US by midweek, but high temperatures may return by the weekend. Authorities warned that children, older adults, and people with certain medical conditions are especially vulnerable to heat-related illnesses, including heat stroke and death. Experts recommended seeking air conditioning, staying hydrated, and limiting time in direct sunlight.
Extreme heat events are amplified by the climate crisis, driven by burning fossil fuels. According to the National Centers for Environmental Information, the continental US experienced its second-hottest first half of the year on record in 2026.
