A massive heat dome is bringing dangerously high temperatures to over 200 million people across the central and eastern United States. The event, coinciding with the official start of summer, is causing daytime highs to exceed 100°F (37.7°C) in many areas, with nighttime temperatures staying above 80°F (26.6°C) in cities—offering little relief.

This extreme heat, caused by a high-pressure system trapping hot air, is expected to last through next week. Health experts warn of increased risks for heat-related illnesses, especially for the elderly, children, outdoor workers, and those without air conditioning.

Several states have issued heat alerts and opened cooling centers. Some cities are enforcing safety rules for outdoor workers, while others, like Florida, have limited local efforts to do so.

Scientists link these intensifying heatwaves to climate change, urging better public protections and long-term planning.

Tips: Stay hydrated, avoid peak heat hours, and check on vulnerable people.