This heat wave isn't just stifling — it's deadly.
And it's expected to continue Friday.
Extreme temperatures Thursday baked a large swath of the country, killing more than a dozen people, at least two police dogs and likely contributing to the death of Franklin the rhinoceros at a Mississippi zoo. Arkansas fire departments were volunteering to hose down overheated cattle, and people as far north as Maine were trying to stay cool.
High school football teams and marching bands practiced indoors or canceled altogether. Tennessee election officials touted air-conditioned polling places as a way to bring in voters, and many cities set up cooling centers for those who needed a break from the sun.
Residents were encouraged to check on their neighbors, especially the elderly.
The scorching temperatures and high humidity made it feel like at least 100 degrees in many places, with heat advisories in effect for 18 states.
"This heat wears on everybody," said Sandy Shamburger, who runs Rankin Sod Farm in Brandon, Miss. "We rigged up lights on a sod harvester so we can work at night."
Still, not even nightfall brings much relief, with temperatures sometimes lingering in the 80s overnight.
The National Weather Service said excessive heat would continue Friday along the Oklahoma-Arkansas border and kept a heat advisory active from Texas to South Carolina.
In Columbia, S.C., 33-year-old Kylin Doster tried to stay under the shade of his umbrella stand as he hustled to serve up steaming hot dogs. He said he works from 10 a.m. to 3 p.m. on Main Street, then sets up outside a biker bar north of town from 11 p.m. to 3 a.m.
"It's really, really hot now, but it even stays hot at night," Doster said. "It don't make any difference. It just stays hot."
The heat has been blamed for at least 16 deaths in Mississippi and Tennessee alone, including a man who had a heart attack while mowing his lawn and a construction worker who was spreading concrete. Maryland authorities on Thursday reported two heat-related deaths from early last week.
Two concrete sections of U.S. Highway 49 in central Mississippi buckled Tuesday, when temperatures hit 103 degrees.
"I can assure you, it was probably 120 degrees on the concrete," said Steve Grantham, assistant district engineer for the Mississippi Department of Transportation.
Animals also have fallen victim. Authorities also said a police dog died Wednesday from heat exhaustion in Tennessee's Blount County after a search for two burglars. A deputy and another dog, also from the Blount County Sheriff's Office, were treated for heat exhaustion. A Fayette County, Ga., handler had also reported his K-9 died because of the heat, said Blount County Sheriff's Department spokeswoman Marian O'Briant.
Heat may have also been to blame for the death of a 37-year-old rhinoceros named Franklin at the Jackson Zoo in Mississippi, where temperatures have surpassed 100 degrees in recent days.
And seven puppies died Wednesday while in the cargo hold of an American Airlines jet in Tulsa, Okla., said airline spokeswoman Mary Frances Fagan.
The heat wave has stretched far beyond the Deep South, where people are more accustomed to long, steamy summers. In the nation's capital, temperatures have hit at least 90 degrees on 45 days so far, said National Weather Service meteorologist Heath Sheffield. There were only 22 such days last year.
Chris and Ingrid Hayes and their three children found Washington hot — though not as toasty as their hometown of Atlanta. They had stopped for a photo in front of the White House earlier in the morning when it was cooler, and they planned to stroll through the National Mall's many air-conditioned museums as the sun began to beat down more intensely.
"We're hoping that helps break up the heat," Ingrid Hayes said.
Carriage tour operators at Philadelphia's Independence Mall were facing the possibility of shutting down early so the horses didn't overheat.
"I've had a couple (of tourists) I thought were going to pass out and die out here," said Kim Hart of 76 Carriage Co. "They were from cooler climates, so they weren't used to it."
Even the northeastern-most corner of the United States has been feeling it this summer. In Portland, Maine, last month was the second-hottest July on record. Billyjo Auger, 24, drinks lots of fluids and sometimes goes for a dip in the cool waters of Portland Harbor.
"There's nothing better than jumping into the water or eating Popsicles," he said this week on a muggy day at the Maine State Pier.
Schools also had to protect children from the heat as classes started again.
At Grady High School in Atlanta, football practice was held indoors this week because of the blazing temperatures and oppressive humidity, said Atlanta Public Schools Superintendent Beverly Hall. Eight high school students at an Atlanta band camp had to be hospitalized for heat exhaustion as the index reached 105 degrees.
In Kentucky, six high school football players were recovering from heat exhaustion after becoming ill at practice Wednesday, said Penny Alderman, assistant principal at Rowan County Senior High School. Other players had to be treated by a school nurse, and practice was canceled, she said.
Erin McCowan, whose 15-year-old daughter, Ebone, attends North Cobb High School outside Atlanta, said her daughter's bus doesn't have air conditioning. But the school district allows children to bring water on the bus and always keeps the windows down, McCowan said.
"The afternoon — it is really hot," the Acworth resident said. "In our subdivision, we have a large hill she has to walk up. She asks me to meet her at the bottom of the hill a lot."