(CNN) -- It's hot. Not "How 'bout this weather?" hot, but buckle-the-pavement, too-hot-even-for-frozen-lemonade, three-showers-a-day hot, and it's that way across a broad swath of the country.
"I just had to stop once in a while and catch a breath, it was just that tough to breathe," said Marion, Illinois, resident Ceasar Maragni, who opted to stay inside Tuesday after a swampy Monday evening trip to the Williamson County Fair. Even the frozen lemonade vendor was lagging with few customers in the nearly 100-degree evening heat, he said.
In central Oklahoma, temperatures were forecast to shoot past the 100 mark for the 14th consecutive day Tuesday, with highs staying that way for nearly another week, according to the National Weather Service.
Crazy demand for water amid the heat wave and problems with soil shrinking as the ground warms has resulted in burst pipes and low water pressure in Oklahoma City, prompting officials to issue mandatory water-use restrictions for the first time in at least a decade, according to utilities department spokeswoman Debbie Ragan.
More than 200 people have suffered from heat-related emergencies in Tulsa and Oklahoma City since June 17, when the agency issued its first heat alert, said Lara O'Leary, spokeswoman for the Emergency Medical Services Authority of Oklahoma.
The heat has been so extreme that a portion of the Cimarron Turnpike in Pawnee County, Oklahoma, buckled on Sunday, creating a 2-foot ramp that sent a motorcyclist flying 150 feet through the air. The searing temperatures are also being blamed in at least one death in Granite City, Illinois.
The National Weather Service issued a heat advisory for parts of 24 states and the District of Columbia, with parts of 10 Midwestern and Southern states getting a more extreme excessive heat warning, as well.
The areas covered by the excessive heat advisory -- parts of Kansas, Oklahoma, Missouri, Arkansas, Illinois, Indiana, Kentucky, Tennessee, Mississippi, Alabama, Georgia and South Carolina -- can expect the heat index to rise above 110 degrees Tuesday, the Weather Service said.
The hottest of the hot looks to be Mississippi and parts of Tennessee, where forecasters warned the heat index could soar to 116.
Other states included in the heat advisory along with Kansas, are Connecticut, Delaware, Louisiana, Maryland, New Jersey, New York, North Carolina, Ohio, Pennsylvania, South Carolina, Texas and Virginia.
In addition to the discomfort and potential danger, the heat could wreak havoc on crops, especially corn, said Chad Hart, assistant professor of agricultural economics at Iowa State University. The heat wave comes at a sensitive time for corn, he said.
"That's why markets are watching the heat wave. We're entering a period of time when corn pollinates, and so if you get a heat wave in the early- to mid-part of July across Iowa, Illinois and Indiana, it can have a big impact," he said.
"The last time we had a big heat wave and drought was in 1988, and that year we saw corn production fall off by over 30% ... so if we think of where we are today with already high corn prices, a true drought scenario can push prices to highs we've never seen before."
While extreme heat is forecast Tuesday as far north as Connecticut -- New York could see a heat index of 103 on Tuesday -- the impact in that part of the country will be short-lived, National Weather Service spokesman Chris Vaccaro said. Temperatures will return to nearly normal summertime levels by Wednesday throughout the Northeast, he said.
High pressure over the Plains is keeping the weather pattern stable, allowing heat to build and expand up the Eastern Seaboard. A cooler, dryer weather system is nibbling at the northern edges of the heat wave, threatening to exchange high temperatures for potentially dangerous thunderstorms, according to forecasters.
There's not quite so much relief in store for residents of the lower Midwest and South.
"This has been going on all weekend and will continue into this week," Vaccaro said.
In Oklahoma City, forecasters are calling for nearly another full week of temperatures above 100 degrees, threatening to break a 1936 record for 22 consecutive days of such heat. And nighttime will bring little solace.
While record- and near-record daytime highs are being set, many areas are also experiencing record warm lows at night. For instance, the low temperature of 83 recorded early Tuesday in North Little Rock, Arkansas, set a new record for the warmest low in July, Vaccaro said.
Warm nights are a problem for people without air conditioning, he said.
"If you're exposed to the outside elements, your body can't cool down at night," he said.
Stillwater, Oklahoma, and Fort Smith, Arkansas, notched Monday's high temperatures across the United States, topping at 107 degrees, the weather service said. At least a dozen cities hit the century mark, with many others well into the 90s.
Several high-temperature records have been broken recently.
Wichita hit 111 degrees Sunday. The National Weather Service says temperatures of 111 degrees have occurred there only 10 times since July 1888.
Forecasters say people should limit outdoor activity during the hottest portions of the day, wear lightweight clothing, drink plenty of water and be watchful for signs of heat exhaustion, which include heavy sweating, pale and clammy skin, weak pulse, fainting and vomiting.
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