Heat Advisory Extended to Thursday Night

North Texas has hit 100 degrees for 11 straight days, and there is no sign of the high heat ending any time soon.

With evening temperatures in Dallas and Tarrant counties not expected to drop below the 80s, the National Weather Service issued a heat advisory for those counties Monday afternoon until Wednesday evening.

The advisory, which will remain in effect until Thursday night, is necessary because overnight low temperatures are not cooling below 80 degrees and heat index values are expected to meet or exceed 105 degrees. 

Surrounding counties where temperatures are expected to fall into the 70s are not included in the advisory.

The expected heat index of 105 degrees may continue into the weekend. 

With the excessive heat, doctors say they expect to see an increase in heat-related illnesses.

Emergency room Dr. Sarah Way, of Texas Health Dallas, said almost all the heat-related illnesses she has seen in the past three weeks have been people who got overheated exercising.

"The things that I'm seeing the most are younger athletes who have been out in the heat -- young men playing football or children doing sports camps and who are forgetting to drink or not taking appropriate breaks," she said.

Way suggests lots of water, along with a sports drink for electrolytes and frequent breaks in the shade.

"Use your common sense. Make sure that if you're going to exercise or be outside that you're picking the times of day where it's not as hot or there's more shade," said Way.

Symptoms of heat exhaustion include dizziness, nausea and muscle cramps.

Doctors also point out that certain medications can make you more likely to suffer from heat stroke.

Heat stroke happens when your body can't cool down and your temperature tops 104 degrees. Most susceptible are infants, seniors and people who work outside.

Sweltering Summer

The temperature setting is stuck on broil across a swath of the Midwest and South, with Dallas and Oklahoma City sweltering through 100-degree heat for at least 11 days in a row.

Forecasters warned on Monday that the extreme heat could continue for most of the week and perhaps beyond.

Dallas recorded its 11th-straight day of 100-degree weather Tuesday. The city hit 100 for nearly three straight weeks as recently as 2006. In 1980, the Dallas-Fort Worth area endured 42 days in a row of 100-degree-and-over heat.

Triple-digit highs are expected through the weekend in Dallas, and there is little chance of rain to cool things down.

"It's breaking daily records, but when you're talking about a record string of days -- we're not there yet," said National Weather Service spokesman Chris Vaccaro. "We're in the midst of a heat wave that's not over yet."

On Monday, 87-year-old R.F. Lanham was taking the heat in stride as he picked weeds in his shaded front yard in Dallas.

"I've seen a lot of hot summers," he said.

As 40-year-old Sally Smith loaded two of her children into her minivan as she left a spin class at a Dallas YMCA, she said that even though she had lived in Texas for 18 years, the hot weather was hard to get used to.

"You feel like your skin is baking," the Michigan native said.

In Keller, boys in summer camp are drinking water every ten minutes to stay hydrated.

"You get so sweaty you just want to pass out but you got to make yourself keep going,” said Houston Miller, a 13-year-old in performance camp. The camp goes on for six weeks and focuses on speed, agility and weights.

"You drink water today for tomorrow," said Coach Cameron Mendoza. "We’re trying to prepare them for football when they put pads on and work twice a day."

Many teams start football practice in about 45 days at the end of August when school starts.

"Some think I’m pretty crazy for being out here but it’s convenient and my office is right off the trail," said Rusty Dean, a cyclist riding along the Trinity River in Fort Worth. "I either have to exercise now (at noon) or not at all, this is when I have the chance."

In Fort Worth, all of the city's pools are closed because of budget cuts. Through a partnership with the YMCA, Fort Worth residents can swim at four of its pools for two hours a day without a membership.

We Are Not Alone

Heat advisories and excessive-heat warnings were issued Monday for 17 states in the Midwest and South. For Tuesday, the National Weather Service issued heat advisories for much of the East Coast, from Georgia to Connecticut, where temperatures are expected in the upper 90s but will feel as hot as 105 because of the humidity.

"It says a lot when you are dealing with such an expansive area of heat alerts," said Vaccaro.

Hutchinson, Kan., had reached 103 by Monday afternoon after hitting a scorching 112 on Sunday. (Records haven't been kept there long enough to tell if it was a new high for the date.) The mercury hit 99 in Joplin, Mo., by the afternoon after topping out on Sunday at 106, breaking the record of 104 for the date, set in 1980.

Oklahoma City has hit 100 degrees or higher -- 110 on Saturday -- every day since June 29, including Monday, making it 13 in a row. The record there is 22 consecutive days of 100 degree-plus weather, set in 1936.

Authorities said a 51-year-old man suffered heat stroke and died Sunday because his mobile home in Granite City, Ill., had no working air conditioner. His body temperature was 104 when he arrived at the hospital.

In Tahlequah, Okla., 56-year-old David Vaughan, who works construction at water treatment plants, said he was using survival skills he learned while working in Kuwait.

"In Kuwait, we had a saying: Walk slow and drink a lot of water," he said.

In El Paso, Texas, 67-year-old Jesus Franco was the grateful recipient of a fan from the Texas Department of Family and Protective Services. Franco, who is blind, said that he had a small air conditioning unit installed in his home last week, but even then, "at night it gets so hot you can't sleep."

As the stream of air cooled his shirtless torso Monday, he said, "This is much nicer."

Felix Cabrera, an employee of the agency giving out the fans, said: "With so many people unemployed and the population getting older, we are getting more calls."

In New Orleans, the heat was, as usual, heavy and suffocating -- but just under 95 degrees, cool enough to allow the mule-drawn carriages to continue riding through the French Quarter. When the mercury hits 95, tourist guides are prohibited from working their mules.

Lorna Taylor, a guide and horse trainer, kept a close eye on her mule, Elvis. She threw snacks into his trough to force him to dunk his head in the water. But she wasn't worried.

"Mules are desert-dwellers," she said, sweat glistening on her brow. "So this is a walk in the park."

NBC 5's Frank Heinz and Kimberly King contributed to this report. Associated Press writers Paul J. Weber in San Antonio, Jim Suhr in Granite City, Ill., Cain Burdeau in New Orleans, Justin Juozapavicius in Tahlequah, Okla., and Juan Carlos Llorca in El Paso also contributed to this report.