Dangerous, record-smashing heat wave to scorch millions

Key Points:

• A dangerous heat wave is expected to intensify across the central to eastern United States this week, with some areas potentially setting all-time high temperature records, according to the National Weather Service and NOAA's Weather Prediction Center.
• Approximately 90 million Americans are currently under extreme heat watches or warnings, with an additional tens of millions under heat advisories; at the peak, about 230 million people—two-thirds of the U.S. population—could be exposed to extreme heat.
• The heat wave is driven by a "heat dome," a high-pressure system causing temperatures to soar 30 degrees above normal, leading to heat indices between 100-115 degrees and limited overnight cooling, increasing the risk of heat-related illnesses.
• The heat dome is expected to persist through the Independence Day weekend and possibly beyond, with some relief anticipated late in the week due to clouds and thunderstorms.
• Authorities advise staying hydrated, avoiding strenuous outdoor activity during peak heat, using air conditioning, and checking on vulnerable individuals, while emphasizing never to leave people or pets in closed vehicles during the heat.