US South blanketed with oppressive heat ahead of holiday weekend

A dangerous heat wave that helped spawn deadly tornadoes threatened to bring more extreme weather to a large swath of the U.S. South on Friday, with the National Weather Service warning Americans from Texas to Florida to limit time outdoors over the long Juneteenth weekend. At least four people were killed in twisters that touched down on Thursday in the panhandles of Texas and Florida, where flooding also forced almost 150 people out of their homes, officials said.

A dangerous heat wave that helped spawn deadly tornadoes threatened to bring more extreme weather to a large swath of the U.S. South on Friday, with the National Weather Service warning Americans from Texas to Florida to limit time outdoors over the long Juneteenth weekend.

At least four people were killed in twisters that touched down on Thursday in the panhandles of Texas and Florida, where flooding also forced almost 150 people out of their homes, officials said. A combination of high humidity and temperatures above 90 degrees Fahrenheit (32 degrees Celsius)could push heat index values above 115 in some parts of the South this weekend, contributing to atmospheric instability and creating conditions ripe for more harsh storms, weather service meteorologist Matt Mosier said.

"It's just been very humid and muggy out," he said. "You'll end up getting strong gusts and large hail, and even with a few of these storms, you can get tornadoes as well." The agency issued excessive heat warnings affecting millions of people in parts of southern Louisiana and Texas, saying the heat index could reach 110 degrees. South Florida and Mississippi were under heat advisories for Friday.

While Southern states are accustomed to high heat, extreme weather conditions have become more frequent across the country and with more intensity, driven by climate change, scientists say. Officials recommended that people drink fluids to keep hydrated, stay in air-conditioned rooms and limit time in the sun.

At least three people were killed and dozens injured by tornadoes in Perryton, Texas, on Thursday. Hundreds of homes were damaged or destroyed, according to local media. Power was out to thousands of customers as of Friday morning, Poweroutage.us said. In Pensacola, Florida, a tornado downed power lines and toppled a tree onto a home, killing one person in their bedroom, Escambia County spokesperson Davis Wood said. Heavy rainfall also forced 146 residents to evacuate an apartment complex in the city of Warrington, he said.