Sweltering heat wave bakes US South

A prolonged heat wave kept its grip on the US South on Tuesday as dangerously high temperatures rising well above 38 Celsius and oppressive humidity were on tap across a wide swath of the region through the holiday weekend.

Some 62 million Americans in central Arizona across through Texas and the Deep South and into Florida's panhandle were under excessive heat watches, warnings and advisories that were expected to last until the Fourth of July, the National Weather Service said.

"There may be more danger than a typical heat event, due to the longevity of elevated record high nighttime lows and elevated heat index readings during the day," the NWS said in an advisory. "It is essential to have a way to cool down and interrupt your heat exposure."

Heat index temperatures were forecast to reach 110 degrees in Dallas, 111 degrees in New Orleans and 107 in Mobile, Alabama on Tuesday, the service said, urging people across the region to stay out of the sun and drink plenty of fluids.

A stationary high pressure system that is trapping the heat and humidity, known as a heat dome, has been hovering over the US South for the last few weeks, causing the sweltering weather.

The heat wave claimed the life of a 14-year-old boy who was hiking in the Big Bend National Park in Texas on Friday when the temperature reached 119 degrees. His stepfather was killed in a car crash when he went to get help, the park said in a statement.

The growing frequency and intensity of severe weather across the US is symptomatic of human-driven climate change, climate scientists say.

As of midday on Tuesday, no widespread power outages were reported in the region. However, some 125,000 homes and businesses remained without electricity in Arkansas, Tennessee and Oklahoma after strong storms over the weekend took down power lines, according to poweroutage.us.