A heat dome is bringing dangerous, persistent heat to central parts of the United States, with forecasters warning that high temperatures, humidity and warm nights could increase the risk of heat-related illness. The conditions matter because limited overnight cooling can prevent people from recovering from daytime heat, allowing heat stress to build over several days.

Around 80 million people were facing heat advisories, with the affected area stretching from Dallas to North Dakota and extending across the Southwest, Great Plains, Midwest and Gulf Coast. Temperatures were forecast to run about 10–15°F (6–8°C) above normal in some areas, while western Nebraska could reach 108°F (42°C); high humidity was expected to make it feel hotter.