A widespread heat wave is building across the United States, with forecasters warning of oppressive conditions beginning in the Southwest and Great Plains over the weekend. Multiple outlets report that triple-digit temperatures are expected in parts of these regions, then spread eastward as a “heat dome” of high pressure develops. Meteorologists say the dome can trap hot air, keeping temperatures elevated for an extended period—potentially a week or more. Coverage describes unusually warm conditions for many areas, with forecasts indicating temperatures roughly 15 to 25 degrees Fahrenheit (8 to 14 degrees Celsius) above normal in some locations, including nighttime. Several reports highlight health risks associated with the lack of overnight cooling, noting that people may not get a chance to recover from daytime heat. The National Weather Service is cited in one account warning of extreme temperatures in specific locations and advising residents to take precautions. Across the reporting, the recommended actions are consistent: stay hydrated and find ways to cool off during the hottest hours, especially for vulnerable populations.