Millions of Americans are planning to attend Fourth of July parades, barbecues, and fireworks displays this weekend, but meteorologists warn that spending time outdoors could be dangerous as an intense heatwave brings record-breaking temperatures to central and eastern states. The National Weather Service expects a strengthening heat dome to build across the center of the nation and gradually expand eastward this week, producing temperatures in the 90s and low 100s Fahrenheit (30s Celsius). The bigger concern, however, will be wet bulb temperatures. The combination of extreme heat and high humidity will make it feel as hot as 115 degrees F (46 degrees C) across parts of the southern Plains, the mid-Mississippi Valley, and eventually the Mid-Atlantic, according to the NWS. “No exaggeration to say that the severity of the heatwave that the Eastern U.S. is about to experience will be cruel and grueling for days!” Jeff Berardelli, chief meteorologist and climate specialist for WFLA Tampa Bay, posted on X on Sunday. “[Hundreds] of record highs, some neck and neck with all-time records, in the East Coast cities!”
Heads up‼️ Hottest Ever?! It’s genuinely possible. No exaggeration to say that the severity of the #heatwave that the Eastern US is about to experience will be cruel and grueling for days! 100s of record highs, some neck and neck with all-time records, in the East Coast cities!… pic.twitter.com/pX5XdjlbDV — Jeff Berardelli (@WeatherProf) June 28, 2026 Why hot, humid weather is so dangerous Much of the central and eastern U.S. will be under a Moderate to Major HeatRisk (the NWS index for potential heat-related health risks) for Monday and Major to Extreme HeatRisk for Tuesday, the agency stated Monday morning. On the Fourth of July, more than 60 million Americans across the East—including major cities such as New York, Philadelphia, Washington, D.C., Charlotte, Cincinnati, and Nashville—will be under Extreme HeatRisk.
