This story was updated Thursday, Aug. 15, 2019, at 1:45 a.m. to change the Tuesday high temperature from 99 to 100 degrees.
It was the hottest day of the year so far in Chattanooga.
On Tuesday, the high reached 100 degrees, with the heat index topping 109, according to WRCB-TV Channel 3 Chief Meteorologist Paul Barys.
It was a similar scene across the South as heat advisories extended from South Carolina to Texas.
The warnings came one day after the temperature and humidity combined for a Monday heat index of 121 in Clarksdale, Mississippi. The heat index is what the temperature actually feels like.
Among the major worries were heat exhaustion and heat stroke, according to the Centers for Disease Control and Prevention.
In Chattanooga, the Salvation Army location on East 28th Street was distributing box fans and bottled water to low-income people this week, while the McCallie location was offering a "hydration station."
Hamilton County Schools on Tuesday recommended schools keep children inside for recess and outdoor activities, according to district spokesman Tim Hensley, and some local day cares also kept little ones in from the heat.
With high school football getting into full swing this week, player safety was also a concern.
Hensley said coaches would be monitoring heat indexes and following guidelines for outdoor practices. The Tennessee Secondary School Athletic Association, the state's governing body for all high school sports, has a heat policy that says all outdoor play must be stopped when the heat index reaches 104.
By Tuesday afternoon, most outdoor practices had to be rescheduled, according to one school board member.
The local prep jamboree will be played Friday and Saturday at Finley Stadium, with Friday games beginning at 5:30 and Saturday's first quarter beginning at 3:30 p.m. The high Friday is expected to be around 90, with Saturday reaching 94.
Temperatures are expected to cool a bit Wednesday, with highs reaching the upper 80s to 90, Barys said.
"It won't get so hot," he said Tuesday afternoon. "It's a short-term heat wave, and it'll cool down [Wednesday], and Thursday it'll be near 90 and Friday near 90, which is seasonable. The main thing is cooler weather is on the way."
Elsewhere across the country, the heat was taking its toll.
In Kansas, a 2-year-old boy died after he was found alone in a parked car in the afternoon heat Sunday. It appears heat played a role in the child's death, Lawrence Police Chief Gregory Burns Jr. said in a statement Monday. It was about 88 degrees with a heat index of 96 in Lawrence at the time, the weather service said. The police investigation is continuing.
In Spartanburg, South Carolina, the Carolina Panthers and Buffalo Bills are practicing together Tuesday and Wednesday before a preseason NFL game in Charlotte, North Carolina. Over the weekend, Panthers coach Ron Rivera had some fun with Bills coach Sean McDermott, sending a screenshot of the heat index in Spartanburg. It showed 110 degrees along with an orange emoji face dripping with sweat.
"A psychological game," Rivera joked of the scorching heat that awaits McDermott and the Bills this week.
In downtown Birmingham, a piano-playing sidewalk evangelist sought refuge from the sun with two umbrellas — one over his head and the other on his sunny side.
Around the corner, artist Henry L. McShan sold his watercolor landscapes in a shady spot beside a park. Temperatures in Birmingham were already in the 90s Tuesday morning.
"I'm going to be here all day. I've got several bottles of water. I'm ready for it," said McShan, his face glistening with sweat.
In Texas, TXU Energy asked its customers to dial back their thermostats between 2 and 6 p.m. Tuesday due to the extreme heat. The Electric Reliability Council of Texas, which oversees parts of the state's power grid, said it set an all-time peak demand record Monday afternoon.
The Dallas Zoo prepared for large crowds Tuesday during $1 admission day even as forecasters predicted triple-digit temperatures. A Dallas Zoo dollar admission day in July drew more than 30,000 visitors, with temperatures in the 90s, zoo spokeswoman Chelsey Norris said.
Misting tents were set up throughout the zoo for visitors to cool down. Elephants will be soaked with water cannons and offered frozen treats, she said.
The Associated Press contributed to this story.