(CNN) -- It's truly the dog days of summer in the South.
The heat wave that has encompassed many Southern states this week is not expected to loosen its grip in the coming days.
Scorching high temperatures are in the forecast over the weekend in the North.
Topeka, Kansas; Kansas City, Missouri; Omaha, Nebraska; and Oklahoma City are several cities under an excessive heat watch Friday through Sunday.
And little relief is expected next week.
An area of high pressure is anticipated to circulate hot and humid air over much of the central and eastern part of the country, the National Weather Service said in a statement Thursday night.
"Heat index values in excess of 110 degrees are likely," it said.
Extreme heat indices -- how the air feels, with heat and humidity -- are expected to reach up to 116 degrees in Minneapolis next week.
"These are extreme out-of-the-ordinary temperatures for Minnesota," CNN meteorologist Sean Morris said.
Dallas, Fort Worth, Arlington and other areas in Texas experienced afternoon heat indices of 105 degrees or more through Thursday.
The month of June was the hottest recorded for Texas since 1895, according to the National Weather Service.
Lawton, Oklahoma, and Wichita Falls, Texas, shot past the 100 mark for the area's 16th consecutive day of triple-digit heat Thursday. 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.
The heat has driven up the demand for water and shrunk soil, resulting in low water pressure and burst pipes in Oklahoma City. Officials issued 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.
Forecasters say people should limit outdoor activity during the hottest times of day, wear lightweight clothing, drink plenty of water and watch for signs of heat exhaustion, which include heavy sweating, pale and clammy skin, a weak pulse, fainting and vomiting.
At the peak of the past week's heat wave, more than 20 states from the Plains to the Northeast were under heat advisories.