A dangerous and prolonged heat wave is forecast to envelop the eastern half of the United States in the final days of July, placing millions at risk from heat-related illnesses.
A dome of high pressure, combined with abundant atmospheric moisture, will trap heat and push “feels like” temperatures to between 110 and 115 degrees. According to the National Weather Service, daily highs will reach the upper 90s to near 100 degrees, while warm overnight lows in the 70s will offer little relief. The agency warned that the long duration and high humidity would lead to an increased danger, with heat risk expected to remain in the major to extreme categories through the end of the month.
The most persistent heat is expected across the Tennessee Valley, the mid-South, the Southeast, and into the Carolinas. The Midwest, Ohio Valley, and mid-Atlantic will also experience hotter-than-normal temperatures in the 90s before a potential cold front brings some cooling around July 30 or 31. In addition to the heat, atmospheric interactions around the perimeter of the high-pressure system are forecast to trigger severe thunderstorms and heavy rain.
Experts emphasize that this event reflects the broader impacts of climate change. “We’ve always had heat waves,” said Max Holmes, president of the Woodwell Climate Research Center. “But it’s happening a lot more, with greater intensity, greater duration and greater frequency. This is exactly what we expected to happen.”
Data from the National Oceanic and Atmospheric Administration (NOAA) shows that June 2025 was the seventh-hottest June on record. Average U.S. temperatures in July have trended approximately 2.7 degrees warmer since 1950. Critically, average overnight temperatures have climbed even more than daytime highs, preventing the environment from cooling down and intensifying the next day’s heat.
An analysis by Climate Central concluded that human-caused climate change made the recent excessive heat at least three times more likely for nearly half the U.S. population. “This is not your grandmother’s heat wave,” said Kristina Dahl, the organization’s vice president of science. “Climate change is making this heat wave significantly hotter — and therefore more dangerous — than heat waves of the past.”
Prolonged exposure to such conditions can cause life-threatening complications. Scientists now use “wet bulb” temperature—a measure that accounts for humidity’s effect on the body’s ability to cool itself through sweat—to assess risk. While previously thought that humans could tolerate wet-bulb temperatures of 95 degrees at 100% humidity, a 2022 Penn State study found the actual limit is closer to 87 degrees, even for young, healthy individuals. The threshold is likely even lower for vulnerable populations.
The American Red Cross advises that anyone who must be outdoors take extra precautions. Key recommendations include:
- Identify those at risk: Be mindful of older adults, young children, pregnant women, and individuals with chronic health conditions.
- Stay hydrated: Drink water frequently, even before feeling thirsty, and avoid alcohol, caffeine, and sugary drinks.
- Stay cool: Seek air-conditioned spaces, limit outdoor activity, and wear lightweight, loose-fitting clothing.
- Act quickly: If someone shows signs of heat exhaustion or stroke (cramps, heavy sweating, dizziness, nausea), move them to a cooler place, use wet cloths to lower their body temperature, and have them sip water.
Access to official heat-related information has reportedly become more challenging. A heat risk tracking tool from the Centers for Disease Control and Prevention (CDC) is no longer active. Critics also point to changes in language on the Environmental Protection Agency website and the termination of hundreds of grants mentioning climate change.
Furthermore, NOAA’s proposed budget indicated it would no longer support the National Integrated Heat Health Information System (Heat.gov), a comprehensive federal resource. For now, the website remains online.
“There are combinations of temperature and humidity the human body just can’t tolerate,” Holmes said, criticizing the obscuring of factual data. “Trying to hide the truth doesn’t help people. It’s shameful that our government is doing so. It’s not a partisan thing, it’s a fact thing.”
