A powerful heatwave gripped central and southern parts of the United States over the weekend, placing at least 40 million people under extreme heat warnings as heat indexes soared well above 100°F (38°C) from Minnesota to Mississippi and as far west as California and Nevada. The extreme conditions are being driven by a heat dome — an atmospheric phenomenon that traps and intensifies heat — with parts of the southwest expected to reach 120°F (49°C); Rapid City, South Dakota, recorded an all-time high of 112°F on Saturday. The event is raising serious public health concerns, particularly for children, the elderly, and unhoused people, and comes as the continental US recorded its second-hottest first half of a year on record in 2026, with scientists noting that such extreme heat events are made more frequent and severe by climate change.