( CNN ) -- A blistering heat wave retreated to the south Wednesday , bringing some relief to the Ohio Valley and northeastern United States . The number of states under heat advisories has diminished to 12 -- half the number earlier in the week . Dangerous heat is expected across parts of northern Texas through Thursday evening , according to the National Weather Service . Dallas , Fort Worth , Arlington and other areas will experience afternoon heat indices of 105 degrees or more through Thursday . Other states still sweltering under heat advisories include Oklahoma , Louisiana , Arkansas , Missouri , Tennessee , Mississippi , Alabama , Georgia , South Carolina , North Carolina and Virginia . Many Tennesseans should expect the heat index to be between 110 and 114 degrees for the rest of the week , according to the National Weather Service . `` 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 . Other areas of the country not under heat advisories touted new record highs Tuesday . Newark , New Jersey , broke its previous record of 98 , set in 1966 , when it hit 99 degrees . JFK Airport and Islip , New York , did the same , reporting 97 and 93 degrees respectively , beating 1993 records of 94 degrees at JFK and 91 in Islip . In central Oklahoma , temperatures in some places shot past the 100 mark for the 14th consecutive day Tuesday . Highs in much of the state are likely to flirt with triple-digits for almost another week , according to the National Weather Service . High 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 . This prompted 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 . 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 . '' Temperatures will return to nearly normal summertime levels by Wednesday throughout the Northeast , said Chris Vaccaro , a spokesman for the National Weather Service . High pressure over the Plains is keeping the weather pattern stable , allowing heat to build . 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 near or above 100 degrees , threatening to break a 1936 record for 22 consecutive days of such heat . 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 ca n't cool down at night , '' he said . The heat has already claimed at least one victim , a 51-year-old man in Granite City , Illinois , who died Sunday because of the excessive heat , according to the Madison County coroner . 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 . CNN 's Monica O'Connor , Meteorologist Jacqui Jeras , Ed Payne , Karen Smith and Chelsea Bailey contributed to this report .
The National Weather Service has taken down heat advisories in some states . High pressure over the Plains is keeping the weather pattern stable , allowing heat to build . The heat wave could harm crops , especially corn . Comment: