A major heat wave is predicted to engulf the United States, threatening to break temperature records nationwide. PBS reports that almost the entire country will experience unseasonably high temperatures, prompting meteorologists to caution that this could be one of the most severe heat waves in recent history, with serious implications for public health. The National Weather Service has issued heat advisories and excessive heat warnings for many states, advising people to stay hydrated, seek air-conditioned spaces, and reduce outdoor activities during the hottest parts of the day. Vulnerable groups, such as the elderly, children, and those with chronic illnesses, are receiving special attention.