US bakes under coast-to-coast heat dome

A heat dome with temperatures exceeding 100 degrees Fahrenheit (37.8 C) is stretching across the United States, affecting more than 100 million people in 15 states, and is expected to intensify throughout the weekend.

Death Valley National Park, which straddles the California-Nevada border and is known as one of the hottest places on Earth, had its highest temperature recently surpass 130 F (54.4 C). Nighttime low temperatures in Death Valley are forecast to exceed 100 F.

"Dangerous heat will result in a major to extreme risk for heat-related illnesses for much of the population, especially those who are heat sensitive and those without effective cooling and/or adequate hydration," said the National Weather Service in Hanford, California.

In South Florida, temperatures are expected to exceed 105 F, the National Weather Service said. Unlike the West region, the Sunshine State is more humid.

The ocean temperature near the Florida Keys has surged beyond 90 F, according to the National Oceanic and Atmospheric Administration.

Such warm water temperatures "would be impressive any time of year, but they're occurring when the water would already be rather warm, bringing it up to bona fide bathtub conditions that we rarely see", Brian McNoldy, a senior research associate at the University of Miami and a hurricane expert for Capital Weather Gang, told The Washington Post.

Meanwhile in Vermont, the state prepared for the next round of storms — and possibly a tornado — as people took advantage of calm weather on Thursday to clean up from historic flooding that damaged thousands of homes, businesses, and roads, and left some residents stranded.

As floodwaters receded, the good news was that there were no new rescue missions, dams were holding up and more roads reopened. The bad news was that strong thunderstorms were expected to move into parts of the state by Thursday night, which could cause more flash flooding, Governor Phil Scott said.

Conditions could spawn a tornado, he said. And the state could get more heavy rain over the weekend.

Agencies contributed to this story.